Based on the data of science-based SMEs listed on China’s National Equities Exchange and Quotations over the period 2011-2023, this study utilizes the exogenous shock of local governments’public data opening to test its impact on corporate financing constraints and the underlying mechanism. It is found that government data opening significantly alleviates the financing constraints of science-based SMEs by reducing information asymmetry and strengthening the monitoring effect, and this alleviation is more significant when the overall quality of government data opening is higher, the data quality is better, the platform function is stronger, and the regulations and policies are better. Heterogeneity analysis shows that the alleviation effect of government data opening on financing constraints is more significant for non-state-owned enterprises, firms with lower collateral abundance, and enterprises located in regions with weaker intellectual property protection. Moreover, government data opening can improve firms’ credit accessibility, extend their financing maturity, and enhance their innovation capabilities.