To ensure food security, the focus has shifted from increasing food production to transforming and upgrading the food industry, and retaining the added value of the food industry and its main entities in the production areas is an effective way to increase the enthusiasm for grain production in these areas. Using the gravity model, this study analyzed the evolution trends and spatiotemporal coupling degree of the gravity centers of grain production and processing at the national level from 2017 to 2020, and evaluated the spatial pattern of the coupling and coordination level between grain production and processing in China. The results showed that the agglomeration gravity center of grain production in China has generally shifted northwestward, while the agglomeration gravity center of grain processing has generally shifted northeastward. The gravity centers of grain production and processing have overall shifted northward, showing consistency in their movements, with the migration distance of the agglomeration gravity center of grain processing being greater than that of grain production. The spatial distance between the agglomeration gravity centers of grain production and processing has been decreasing yearly, indicating better spatial coupling between grain production and processing. Major grain-producing provinces should leverage their advantages in grain production and tap into the development potential of the grain processing industry.