Technological innovation is the foundation of a nation. The government formulates appropriate policies at different stages in order to encourage enterprises to participate in innovation activities, improve their core competitiveness, and promote the transformation and upgrading of industrial structure. Based on the data of listed companies in Guangdong Province from 2005 to 2017, this paper uses a counting model to empirically analyze the impact of prefecture-level city government science and technology policies on corporate innovation and its mechanism. Research shows that: Science and technology policies can improve the innovation level of enterprises; The incentive effect of science and technology policy is mainly produced through the intermediary variable of R&D intensity; Science and technology policies can not only promote the strategic innovation of enterprises, but also promote the substantial innovation of enterprises; Direct incentive policies have no significant impact on corporate innovation, while indirect incentive policies that create an innovative atmosphere have a significant positive impact on corporate innovation; The positive effect of policy incentives on non-state-owned enterprises and non-high-tech enterprises is more obvious.