A new round of scientific and technological revolution and industrial transformation is developing in depth, realizing self-reliance and self-improvement in science and technology, consolidating the core position of innovation in the overall modernization of China, and urgently accelerating the construction of scientific and technological financial system. Taking the pilot policy of integration of sci-tech and finance as a quasi-natural experiment, based on the data of 274 cities from 2003 to 2018, this paper measures the integration level of technology and finance of cities, and further uses the PSM-DID method to evaluate the promotion effect of pilot policies on the integration level of sci-tech and finance. The results showed that: the pilot policy is conducive to make up for market failure, form policy guidance and capital crowding effect, share innovation risk, significantly improves the integration level of sci-tech and finance of pilot cities, the other regression results are also robust; there is no obvious regional heterogeneity, but due to the base period effect, the pilot policy has a greater impact on the central and western regions; the pilot policy mainly promotes the integration level of sci-tech and finance of the pilot cities through policy sci-tech finance, market sci-tech finance and the interaction between them. This study has a good reference value for the efficient combination and policy-making of Sci-tech and finance.