This article uses panel data of Chinese listed companies from 2010 to 2019 and adopts a multi-period difference-in-differences approach to investigate the impact of the establishment of free trade zones on corporate financing constraints. The research finds that the establishment of free trade zones can alleviate corporate financing constraints, and this conclusion still holds after a series of robustness checks. Further heterogeneity analysis reveals that the alleviation of financing constraints for state-owned enterprises is stronger than that for non-state-owned enterprises, and the establishment of free trade zones can significantly alleviate financing constraints for non-high-tech enterprises, but the impact on financing constraints for high-tech enterprises is not significant. Mechanism analysis results show that free trade zone policies alleviate corporate financing constraints through the pathways of promoting corporate innovation and foreign direct investment, and the improvement of financial development plays a significant synergistic role in alleviating corporate financing constraints in the free trade zone. The conclusion provides valuable policy basis for alleviating corporate financing constraints under the strategic background of high level opening up.