Government policies serve as a key institutional force in guiding and advancing socio-economic development. Taking the “national digital economy innovation and development pilot zones” as a quasi-natural experiment， this paper investigates the impact of place-based policy support on the high-quality development of the regional digital economy and its underlying mechanisms. First， a comprehensive evaluation index system for the high-quality development of the digital economy is constructed. Based on panel data from 31 provinces in China from 2013 to 2022， this study statistically analyzes the dynamic evolution and regional disparities in the high-quality development of China’s digital economy. Second， a difference-in-differences model is employed to empirically examine the effects of policy support on the high-quality development of the regional digital economy. The findings reveal that the pilot zone policy exerts a significant positive impact， with notable spatial heterogeneity in its effects. Mechanism analysis indicates that the policy enhances high-quality development primarily by increasing fiscal investment in science and technology and promoting the optimization and upgrading of industrial structures. This studyprovides a theoretical and empirical basis for evaluating the high-quality development of regional digital economies and understanding the role of policy support， while offering policy references for strategy formulation and coordinated regional growth.