Abstract:  Innovation based on digitalization has been become a hot issue in the economic strategy in various countries. In the construction and development process of Digital China, it is the key to achieve innovation-driven development by improving regional digital level and highlighting the effectiveness of Digital China construction. The theoretical research on the interaction between digitalization and innovation performance is still in the development stage, for mainly focusing on the way and degree of the impact of informatization on innovation. Since there are some differences between digitalization and informatization, further research is needed on the impact of regional digitalization level on innovation performance. In addition, most of the existing research on the evaluation of regional innovation performance is at the national and provincial levels, and lack of empirical research at county level.To remedy the above gaps in present studies on the impact of the digitalization level on innovation performance, this paper firstly identifies the dimensions of regional digitization level, by putting forward four dimension measures: digital access, digital equipment, digital platform and digital application. Then, the research hypothesis is put forward through theoretical analysis to study empirically the impact of regional digitization level on innovation performance from the four aspects: (1) The improvement of regional digital access level is conducive to improving regional innovation performance. (2) There is an inverted U-shaped relationship between the regional digital equipment level and regional innovation performance. (3) There is an inverted U-shaped relationship between the regional digital platform construction level and the regional innovation performance. (4) There is an inverted U-shaped relationship between the level of regional digital application and regional innovation performance.In order to test these four hypotheses, this research collects panel data of 73 counties (districts, cities) in Zhejiang Province from 2015 to 2017, and constructs a regression model to which contains explanatory variables with four dimension measures, the number of regional innovation achievements (measured by the number of patent applications) and the quality of regional innovation achievements (measured by the number of patent grants) as explained variables and the level of regional economic and social development as control variables. The model is analyzed by utilizing the fixed–effects negative binomial regression models. The empirical results show：(1) The level of digital access is conducive to promoting the improvement of regional innovation performance, and more attention needs to be paid to the improvement of digital access. (2) The influence of digital equipment level on regional innovation performance shows an inverted U-shaped relationship. Excessive investment in digital equipment level may not be conducive to the improvement of regional innovation performance. (3) The impact of digital application level on regional innovation performance shows an inverted U-shaped relationship. Excessive investment in digital application level may not be conducive to the improvement of regional innovation performance. (4) The influence of digital platform construction level on regional innovation performance shows an inverted U-shaped relationship. Excessive investment in digital platform construction level may not be conducive to the improvement of regional innovation performance.The theoretical significance of this paper is as follows: (1) measuring regional digital level from four dimensions, such as digital access, equipment, platform construction, and application-level, help to further deepen the theoretical cognition of digital level, and lay a conceptual foundation for subsequent empirical research; (2) empirical research based on panel data of Zhejiang county level reveals the non-linear relationship between regional digital level and innovation performance efficiency, further promotes and enriches the theoretical achievements in this field. At the same time, based on the research results, this paper has the following management implications: first, local governments should strengthen the overall planning of digital construction and promote the deep integration of digital and innovation. Second, digital technology can be utilized to improve innovation environment and promote innovation development; third, digital construction ("hard" construction such as digital platforms and "soft" construction such as digital talents) can promote urban-rural integrated development to make full use of the existing digital resources and alleviate the uneven development of regional innovation. And finally, in the process of digital construction, we need to pay attention to the input-output efficiency and give priority to overall interests, in order to avoid over-investment of resources. The above enlightenment has positive practical significance for promoting regional innovation and industrial digital transformation by digital construction.

Key words:  digital level, regional innovation, transformation and upgrading, patent