Abstract: The construction of high-standard basic farmland, as an important starting point of “storing grain in land and technology”, plays an important role in promoting agricultural and rural modernization and the mechanization of staple grain production. Treating the high-standard basic farmland construction policy as a quasi-natural experiment, and based on a provincial panel data, this paper employs a continuous difference-in-differences (DID) model to analyze the impacts of the high-standard basic farmland construction policy on the mechanization level of staple grain production and its mechanism. Results show that the implementation of the policy can significantly improve the mechanization level of staple grain production, and this promotion effect shows a steady and progressive trend over time. From the analysis of heterogeneity, there are better policy implementation effects in eastern areas with higher levels of economic development, areas with less relief, and areas with higher levels of construction. In addition, the policy implementation has a better effect on the mechanization of mechanized ploughing and corn production. The mechanism test shows that the high-standard farmland construction policy improves the mechanization level of staple grain production by expanding the scale of farmland management, changing the agricultural planting structure and improving the rural transportation infrastructure. Based on the research findings, this paper recommends intensifying the development of high-standard farmland in accordance with local conditions, prioritizing improvements to agricultural machinery operating conditions, ensuring high-quality arable land is reserved for grain production, and further strengthening national grain security safeguards.