Abstract: Can the construction of smart cities that promote high-quality development narrow county economic inequality? We used per-capita light intensity data from satellite inversion to calculate 21-year Gini coefficients for 2,851 counties in China, and examined the impact of smart city on county economic inequality and its mechanism by taking China's smart city pilot as a quasi-natural experiment. The findings are as follows: (1) Smart cities in China can reduce county economic inequality, and the results remain stable after testing; (2) Heterogeneity analysis shows that for counties with smaller city size and better economic development, smart city is more conducive to reducing economic inequality; (3) Mechanism analysis shows that the technology effect brought by smart city reduces the county economic inequality by improving the level of regional innovation, and the allocation effect reduces the county economic inequality by balanced allocation of capital factors and marginal allocation of land factors.