Abstract:      Innovation is the main driving force that enables our country′s rapid growth economy to transform to high quality development and key core technology to develop into the forefront of innovative countries, but at present the development has fallen into the innovation predicament of "sufficiency in quantity but lack in quality". To this end, China has set up a number of pilot innovative cities and expected to promote the regional integral innovative development by taking the surface with the point.
     The research around innovation-oriented cities has attracted much attention from scholars. This paper summarizes the innovation measurement methods and related research literature of innovation-oriented cities. Then the overview finds that the existing methods to measure innovation level focus on the measurement of comprehensive innovation performance and innovation quantity level, and the research on innovation quality is not comprehensive enough. Moreover, there is a lack of research on the policy effect of innovation-oriented cities based on the perspectives of innovation quantity and innovation quality.
    Through research and analysis, this paper puts forward some theoretical hypotheses from three aspects: the establishment and innovation ability of innovative cities, the heterogeneity of innovation effect and the internal mechanism of influencing innovation, and constructs quasi natural experiments based on the panel data of cities at prefecture level and above in China, respectively with patent application number of innovation quantity, material innovation, sustainable innovation and collaborative innovation of industry-university-research as the dependent variable, taking whether to be an innovation-oriented cities as the independent variable. After using the multi-period differential model to conduct research, the results show that the establishment of innovation-oriented cities not only increases the quantity of innovation, but also promotes the improvement of innovation quality. By a series of robustness tests, the results are still robust.
     The heterogeneity analysis shows that the impact of the establishment of innovative cities on the quantity and quality of urban innovation is different between different locations and different levels of cities. The pilot policies have a significant positive impact in the east and south regions, and a low significant impact in the central and western regions, but no significant impact in the northern regions. In the first-tier and second-tier cities, the effect is significantly positive, while in the third-tier cities, the effect coefficient is positive but not significant, and the effect coefficient gradually decreases with the decrease of the city level. Further analysis shows that the establishment of innovative cities has a significant spatial spillover effect, which can not only improve the innovation capacity of local cities, but also promote the innovative development of surrounding areas.
     In order to test the internal mechanism of innovation-oriented cities policy, this paper explores the mediating effect of attracting high-quality human resources and upgrading industrial structure as the mediating variables. The empirical results show that they play a certain role in transmission, but the effect only accounts for 40%.
    In the future, we should continue to support the construction of innovation-oriented cities, develop innovation capacity according to local conditions, and promote diversified development of innovation paths.

Key words:  innovative city, innovations quantity, innovation quality, heterogeneity analysis