Abstract:    Due to the unreasonable division of global value chains, irrational economic structure and imperfect legal system, China′s rapid economic growth is accompanied by increasingly prominent environmental pollution and increasingly severe ecological hazards. How to improve the ecological environment, explore the path of environmental pollution control, has gradually become an important issue for the government to solve. In this context, the government actively advocates to establish a green innovation system, and take innovation as the guide to drive green development. However, enterprises are the important carrier of technological innovation and the backbone of scientific and technological progress and economic development. Although China′s scientific and technological innovation level and innovation investment have been significantly improved in recent years, and China has gradually entered the forefront of the world, research shows that enterprises are still the main producers and emitters of environmental pollutants. Therefore, whether the technological innovation of enterprises presents the characteristics of environmental friendliness, and whether the development of enterprise innovation activities contributes to the improvement of enterprise environmental benefits and environmental governance has become a new topic of academic concern.
    In view of the gradual internalization of environmental cost, environmental cost has become the most direct means to measure the environmental protection level and pollution control level of enterprises. Based on the sample of Chinese public listed companies in Shanghai and Shenzhen from 2009 to 2016, this paper discusses the impact of technological innovation on the environmental cost of enterprises, examines the environmental orientation of technological innovation, and analyzes the mechanism and influence mechanism of technological innovation on the environmental cost of enterprises. Empirical results show that technological innovation significantly promotes the reduction of enterprise environmental costs, and compared with voluntary environmental costs, technological innovation is more conducive to the reduction of mandatory environmental costs. After controlling the impact of endogenous problems, this conclusion is still stable. Further research shows that the impact of technological innovation on enterprise environmental cost is heterogeneous, and the negative relationship between the technological innovation and enterprise environmental cost is more significant in state-owned enterprises, high-polluting enterprises, enterprises with higher degree of environmental regulation and lower degree of financing constraint.In addition, the conclusion of this paper is still robust after using the double difference method, instrumental variable method and other robustness tests to alleviate the endogenous problem. This study verifies the environmental orientation of technological innovation and provides empirical evidence and reference for enterprises to choose investment direction, fulfill social responsibility and government environmental governance.
    According to the previous analysis, we put forward relevant countermeasures and suggestions:
    Firstly, we should enhance the consciousness of enterprise innovation and environmental protection, encourage enterprises to make environmentally friendly green innovations, and promote the transformation of enterprises environmental behavior from negative end management to positive front prevention. It should give full play to the "gain" effect of green innovation, and effectively promote enterprises to improve unit energy efficiency, reduce energy consumption, reduce the emission of environmental pollutants, and thus promote the reduction of enterprise environmental costs and even production costs.
    Secondly, it should strengthen the environmental regulation intensity of the government and the public′s, and the appropriate environmental regulation is conducive to promote the enterprise to carry out innovation. With the increase of government environmental regulation intensity, the cost of enterprises′ compliance with policies and regulations increases. And when the marginal costs brought by the enterprise′s production and operation activities exceed its marginal benefits, it will prompt the enterprise to reduce the environmental costs through technological innovation. At the same time, with the increasing attention of the public and media to environmental problems, fulfilling social responsibility actively has become the key to the long-term development of enterprises. Therefore, informal environmental regulation will also help enterprises to carry out innovation activities, thus reducing the costs of enterprises.
    Thirdly, it is necessary to strengthen environmental supervision to "take the right medicine to the case", take full account of the heterogeneity of enterprise pollution degree and give play to the flexibility of regulatory policies. We will strengthen mandatory environmental supervision over heavy polluting enterprises, promote the transformation and upgrading of heavy polluting enterprises, and encourage non-heavy polluting enterprises to update their emission reduction technologies. At the same time, the government and financial institutions need to strengthen the environmental investment policy. Through government subsidies for environmental protection and green financial business of financial institutions, we can alleviate the capital pressure and financing constraints faced by enterprises in carrying out innovation and environmental protection activities.
    The contribution of this paper is embodied in the following aspects. Firstly, it enriches the economic consequence test of technological innovation. This paper, guided by the impact of innovation on enterprise environmental costs, discusses the environmental and economic consequences of enterprise innovation. It further deepens the understanding of enterprise innovation, and provides decision-making reference for enterprises to fulfill environmental protection responsibilities and governments to carry out environmental governance. Secondly, it broadens the quantitative thinking of environmental cost and analyzes the action path of enterprise innovation on environmental costs. Based on the motivation of enterprise′s environmental behavior, we subdivide enterprise environmental costs into mandatory environmental costs and voluntary environmental costs, and further confirm that enterprise innovation mainly promotes the reduction of the total environment costs by influencing mandatory environmental cost. To some extent, it verifies the "environmental orientation" of enterprise innovation, and makes the path of enterprise innovation affecting environmental costs clearer. Thirdly, it further explored the possible ways for enterprises to improve environmental performance and environmental protection level. From the perspective of micro enterprises, we verify the positive impact of technological innovation on reducing environmental costs by improving resource utilization and reducing pollution emission level. Then it provides micro enterprise evidence for the implementation of innovation-led green development strategy and the choice of investment direction. Lastly, it expands the research depth of the impact of enterprise innovation on environmental cost, and provides empirical evidence of the heterogeneous impact of enterprise innovation on environmental costs. And it provides empirical enlightenment for the development of environmental behavior of enterprises with different pollution degree and environmental regulation intensity.

Key words: enterprise innovation, environmental cost, mandatory environmental cost, voluntary environmental cost, environmental benefit