Hang Chen, Miaomiao Liu, Shuyang Xie, Liupeng Chen
Ensuring food security while advancing agricultural modernization is a strategic priority in China. Using county-level panel data from 2,571 counties in 26 provinces during 2013–2022, this study exploits the phased establishment of national rural industrial integration demonstration parks as a quasi-natural experiment. A difference-in-differences framework, combined with event-study analysis and multiple robustness checks—including tail trimming, placebo tests, shortened sample windows, PSM-DID, exclusion of concurrent policies, and double-machine-learning replacement—is employed to estimate causal effects on grain production. The results show that demonstration park designation significantly increases county-level grain output, with a benchmark effect of about 5.81%, which persists for three years after implementation but gradually declines over time. Mechanism analysis indicates that the policy effect operates mainly through agricultural technological progress and farmland scale operation, while heterogeneity tests reveal stronger impacts in counties with higher fiscal expenditure and greater internet penetration. These findings suggest that rural industrial integration can enhance grain production by promoting technology diffusion and land-use optimization, and that policy effectiveness is contingent on fiscal and digital conditions, highlighting the need for regionally tailored support when scaling up integration strategies.