Based on the panel data of A-share listed companies from 2016 to 2023, this paper examines the impact of antitrust in the platform economy on collaborative innovation by using the DID method, using the quasi-natural experiment of the Anti-monopoly Guidelines of the Anti-Monopoly Commission of The State Council on the platform economy. The study finds that antitrust in the platform economy can improve the collaborative innovation level of platform enterprises. The mechanism test shows that optimizing the enterprise information environment and industry innovation ecology is an important path for antitrust to affect collaborative innovation in the field of platform economy. Heterogeneity analysis shows that in high-tech industries, enterprises with strong innovation ability and diversified supply chain configuration, antitrust in the platform economy has a more significant effect on collaborative innovation. Further research shows that for the collaborative innovation of different subjects such as industry-university-research institution, intra-group and upstream and downstream of supply chain, antitrust in the platform economy is more helpful to promote the collaborative innovation between enterprises and upstream and downstream of supply chain. Public data opening can form a policy synergy mechanism with antitrust in the platform economy, and jointly promote collaborative innovation of enterprises. Compared with small and medium-sized platform enterprises, the promotion effect of collaborative innovation activities of large platform enterprises under antitrust regulation is more significant; From the perspective of economic consequences, antitrust in the platform economy can promote enterprises to build a safe and stable supply chain by improving the level of collaborative innovation. The research conclusions provide theoretical basis and empirical support for promoting collaborative innovation of enterprises from the perspective of platform economy antitrust.