Abstract:     In the context of open innovation, enterprises are required to build close cooperation relationship with external organizations, thus promoting their technological innovation. The existing literature mainly divides open innovation into two modes: viz., inbound open innovation and outbound open innovation. Based on this classification, some scholars have explored the effects of open innovation on firm performance. However, existing research still needs to be further explored as follows. Firstly, as for the dimension of open innovation, many scholars have focused on the impact of inbound open innovation, yet ignored the role of outbound open innovation. The possible reason is the lack of mature theoretical models for outbound open innovation. Secondly, existing research regarding the internal mechanism between open innovation and enterprise performance mainly focused on the absorptive capacity and market-oriented factors. However, it is pointed out that open innovation would directly or indirectly promote product novelty, and then improve firms′ new product performance. Therefore, this study proposes that product novelty is an important variable affecting the transformation from open innovation into firms′ performance. Thirdly, there are many contingent factors involved in the process of open innovation. On the one hand, the institutional support from government departments can provide knowledge, resources and technology for enterprises. On the other hand, the lack of synergetic mechanism in the process of open innovation will lead to conflicts in many aspects. However, few studies take the two variables as boundary conditions to explore their contingent effect on open innovation. Therefore, this study intends to examine the important roles of institutional support and synergetic mechanism in the process of transforming open innovation into enterprise performance. Based on previous studies, first, this study defines open innovation as two dimensions: inbound open innovation and outbound open innovation, and explores the internal relationship between two open innovation modes and new product performance of enterprises; second, this study examines the mediating effect of product novelty on the relationship between open innovation and new product performance of enterprises; third, this study investigates the moderating effect of institutional support and synergetic mechanism on the relationship above. 
   We used the survey method to collect data using three ways: field investigation, e-mail and alumni investigation. We took innovative enterprises in Shanghai as the research sample in this survey, which involves nine industries. A total of 500 questionnaires were sent out and 242 valid questionnaires were collected, with an effective recovery rate of 48.4%. Then, the reliability and validity test and correlation analysis were carried out in this study. Besides, the relationship between these variables was analyzed by the methods of multiple regression and bootstrap. What′s more, using the Johnson-Neyman method, the moderated mediating effect was shown by four figures.
    This study provided some interesting empirical results. Firstly, the results show that both inbound open innovation and outbound open innovation are positively related to the new product performance of enterprise, and inbound open innovation has a more significant impact than outbound open innovation. This may be due to the fact that enterprises gain more benefits from inbound open innovation than from outbound innovation. More specifically, inbound open innovation has a significant impact on R&D capability, R&D speed, R&D cost and many other aspects of enterprises, while the advantage of outbound open innovation is only bringing financial returns to enterprises. Secondly, the results show that product novelty plays a mediating role in the relationship between open innovation and new product performance of enterprise. Through the inflow and outflow of knowledge, resources and technology, enterprises continuously improve the efficiency of internal innovation and enhance product novelty, thereby ultimately improving enterprises′ new product performance. Thirdly, by constructing a moderated mediating effect model, this study confirms that institutional support and synergetic mechanism have moderating effects on the relationship between inbound and outbound open innovation and product novelty, and positively moderate the indirect relationship between "open innovation—product novelty—new product performance". More specifically, the institutional support from government departments can provide resources for innovative enterprises, which are conducive to the reconstruction of the internal resources system of enterprises, thus improving enterprise innovation. In addition, the synergetic mechanism among partners is conducive to promoting the innovation efficiency of enterprises and ensuring the healthy and sustainable development of cooperation. Therefore, under the moderating effects of institutional support and synergetic mechanism, the indirect relationship of "open innovation—product novelty—new product performance" has been effectively strengthened.
    On the whole, as for the theoretical contributions, this study uncovers the "theoretical dark box" between open innovation and firms′ new product performance, expands the boundary conditions of the relationship between open innovation and new product performance of firms, hence enriching the theoretical literature in the field of open innovation. As for the managerial implications, this study provides guidance for enterprises to implement open innovation, and provides important recommendations for government to formulate innovation policy. From the perspective of enterprises, first, enterprises should implement both the inbound and outbound open innovation, and not only acquire knowledge from external organizations but also actively export internal resources rationally. Second, enterprises should pay attention to the establishment and improvement of synergetic mechanism in the process of open innovation. From the perspective of government, first, government needs to further improve the corresponding preferential policies, and further improve the subsidy and incentive policies. Second, government needs to do a better job of service guidance and provides timely industry technology information through the public platform, thus improving the enthusiasm of enterprise innovation.

Key words: two-way open innovation, product novelty, institutional support, synergetic mechanism