Abstract:     Under the unprecedented changes in the world, the external environment of China′s economic development is full of unstable and uncertain factors. Comprehensively improving the level of domestic innovation provides endogenous driving force for coping with complex external changes and promoting China′s high-quality economic development. Implementing good policies at the urban level is an important measure for the government to implement development goals. Industrial convergence is the frontier issue of industrial development and breeds innovation potential. In order to promote industrial convergence, the central government implemented the "Triple Play" reform in pilot cities in June 2010 and December 2011, which provides a quasi-natural experiment for the research of industrial convergence. However, the existing literatures mainly focus on the innovation effect of the industrial convergence on the integrated industries, while ignoring the effect of industrial convergence on urban innovation. Besides, the existing literatures are yet to examine the effect of "Triple Play" reform on urban innovation. Through the theoretical analysis, this paper proposes that "Triple Play" reform could affect urban innovation through the urban informatization and economic agglomeration. This paper utilizes China′s city-level data from 2003 to 2016 for empirical analysis. These data are mainly from China′s Urban Statistical Yearbook and China′s Regional Economic Statistical Yearbook. The pilot information of "Triple Play" reform comes from Notice of the General Office of the State Council on Issuring the List of the First or Second Batch of Pilot Areas (Cities) for the "Triple Play". This paper empirically analyzes the impact and mechanism of "Triple Play" reform on innovation by using difference-in-difference, propensity score matching, difference-in-difference-in-difference and intermediary effect model. Besides, this paper also explores the regulatory role of urban endowments, including technology, Internet and market.
   The benchmark regression results show that "Triple Play" reform has significantly promoted the urban innovation. The conclusion is robust when we consider the parallel trend test and variable measurement method. In order to alleviate the endogenous problem caused by non-randomness of "Triple Play" reform, this paper utilizes the 1:3 nearest-neighbor matching algorithm to match treatment group with the control group, or choose the cities near the pilot cities as the control group, to deal with the selective deviation. Besides, this paper measures the degree of error of missing variables to test the degree of endogenous problem caused by missing variables; this paper alleviates the problem of mission variables by controlling other interference policy, eliminating the samples of special cities and the special years. From the flexible estimations this paper finds that the effect of "Triple Play" reform on innovation has a lag period. Specifically, the innovation level of cities in the treatment group and the control group did not immediately show significant differences until the second year after "Triple Play" reform. The mechanism analysis shows that "Triple Play" reform has contributed to the development of urban informatization and economic agglomeration, which are important factors affecting urban innovation. The regression results of the intermediary effect model show that the urban informatization and economic agglomeration contributed nearly 64% of the improvement of innovation. The heterogeneity analysis shows that urban endowment related to technology, Internet and market plays a key regulatory role. The greater the technological level of the city, the degree of Internet development and the demand of the telecommunications market, the stronger the promoting effect of "Triple Play" reform on urban innovation. 
    This paper provides useful enlightenment for the government to promote innovation through industrial convergence policy. Administrative regulation is an institutional barrier to industrial convergence. The government should take the initiative to sort out the list of systems that hinder industrial convergence. On this basis, the government should actively relax the regulation of industrial convergence through policy pilot. In the pilot process, the government should fully consider the time lag of the reform effect and evaluate the reform benefits from a long-term perspective.
    Invariably, there are many deficiencies in this study, which may also be a topic worthy of further discussion in the future. First, the analysis based on the urban perspective is difficult to investigate the heterogeneous impact of industrial convergence on the innovation of industries, enterprises or other micro subjects. Second, pilot policy might lead to policy discrimination to the non-pilot cities. However, this paper only emphasizes the beneficial impact of "Triple Play" pilot policy on the innovation of the pilot cities and ignores the imbalance of regional innovation that may be caused by the pilot policy.

Key words:  "Triple Play" reform, industrial convergence, innovation, informatization, economic agglomeration