Abstract: Green technological innovation can effectively promote economic transformation, improve the quality of economic development, and is an important driving force for the sustainable development of the world economy. At present, China's green technological innovation capability is worse than that in developed countries. Most green technological innovation in enterprises is induced by external resources or pressure. Research shows that the same technology cannot produce spillover effects. Under the condition of open economy, a country's technological progress not only relies on its own technological innovation, but also on the ability of imitating and absorbing advanced technology from developed countries. With countries become more connected, international technology diffusion effect has become the core factor of technological progress, spillovers of international R&D capital technology plays a more and more important role in independent innovation in developing countries. If China pays more attention to the optimization of technological path and diffusion of green technology in the process of international transfer of technology, China would possibly narrow the gap. This paper mainly researches the impact of technology spillovers of international R&D capital on the efficiency of green technology innovation.Based on the Coe and Helpman’s model of International R&D capital technology spillover (Hereinafter referred to as CH model), this paper divided the international R&D capital technology spillovers into direct and indirect channels. The direct channels include multinational R&D investment and national technology transfer, and the indirect channels include FDI, OFDI and import trade. Then this paper incorporated all channels into CH model and compared the differences of technology spillover effect between different channels. To overcome the endogenous problem that the model may generate, we choose GMM to test the impact of R&D capital spillovers on green technology innovation efficiency. Some conclusions as follows:（1）The one lag of green technological innovation efficiency has a significant effect on the current technological innovation efficiency, and the coefficients are larger than other main explanatory variable, which shows that the cyclic cumulative effect of technology has a significant effect on the improvement of green technological innovation efficiency.（2）International R&D capital technology spillover promotes the efficiency of green technology innovation better than domestic R&D capital does. Except of OFDI R&D capital technology spillover, other channels have promoted the efficiency of green technology innovation, especially the FDI R&D capital. Domestic R&D capital has hindered the efficiency of China's green technology innovation.（3）The details are as follows: Firstly, transnational R&D investment mainly promotes the efficiency of green technology innovation by improving pure technology efficiency, which shows that technology lock-in benefits would reduce the spillover effect of local enterprise. The role of scale efficiency in this progress is relatively small, which shows that the degree of marketization of R&D investment is insufficient. Secondly, FDI R&D capital technology spillover has the most significant effect on the efficiency of green technology innovation. It mainly comes from the improvement of pure technology efficiency. The possible reason is that the imitation effect grew from the flow of talent in foreign-funded enterprises promotes the efficiency of green technology innovation. The scale efficiency is negative because of technology lock-in effect. Thirdly, OFDI R&D capital technology spillover hinders China's technological innovation efficiency, mainly because China's green technology acquisition OFDI accounts for a low proportion. Fourthly, the technology spillover of R&D capital in import trade promotes the efficiency of green technology innovation. It shows that the positive effect of import trade on the efficiency of technological innovation is greater than that of inhibition. In terms of import trade, Chinese enterprises pay more attention to the selection of countries with rich R&D capital. Fifthly, domestic R&D capital hinders the efficiency of green technology innovation. It shows that the allocation of domestic R&D capital investment resources is unbalance, the input of factors is low-end, and has not been transformed into the improvement of green technology innovation efficiency. Based on the above conclusions, this paper puts forward the following suggestions: Firstly, we should pay attention to the cyclic cumulative effect of green technology innovation. As the technology spillover of international R&D capital has a strong cyclical cumulative effect, regions should pay special attention to the cumulative effect of early accumulation of green technology innovation efficiency on later innovation in future development. Secondly, because of the technology lock-in effect in transnational technology transfer, China needs to enhance its independent innovation ability in the future, focusing on the core technology and key technologies with independent intellectual property rights. At the same time, we should strengthen the transnational technology transfer, enhance the degree of marketization, and promote the free flow and efficient allocation of factors. We should gradually increase the patency of R&D investment and foreign direct investment between regions, promote the openness of international trade, and accelerate the diffusion of technological capital. Thirdly, we should make effective use of FDI and optimize the industrial structure of technology importation. In order to introduce high-end technology, we should pay attention to further optimizing the industrial structure, carry out advanced intervention in environmental protection, focus on the development of green industry, and give priority to the introduction of large-scale, intensive and high-tech industries. Improve the skills of R&D personnel and give full play to the positive effect of FDI R&D capital and technology spillover. Improve the quantity and quality of technical talents in local enterprises, enhance the absorption effect of technology and transform the absorbed technology into real products. Fourthly, we should upgrade the level of foreign direct investment and increase the proportion of technology-acquired OFDI. We should encourage investment in sophisticated technology and grasp the trend of international consumption. We should intensify technology-acquiring FDI and strive to absorb R&D capital from developed countries through a variety of investment methods. Fifthly, we should continue to optimize the structure of import trade, increase the proportion of technology-intensive trade, and enhance the technology spillover effect of R&D capital in import trade. Sixthly, we should improve the win-win mechanism of economic growth and environmental protection, and enhance the efficiency of green technology innovation in China. Environmental indicators would be incorporated into the evaluation system of technological innovation efficiency of industrial enterprises, and a green economic development model would be established. We should change the traditional development mode characterized and promote cleaner production mode of enterprises on a large scale, strengthen the application for green label certification, promote enterprises to upgrade the level of green technology innovation, at the same time, make environmental management standardized, routine and scientific.

Key words: international R&D capital, green technology innovation efficiency, Coe-Helpman model, dynamic spatial effect