This study discusses the coupling and coordination relationship among population, economy, and grain production in the central primary grain-producing counties. It aims to find a dynamic balance between the responsibility of the grain-producing areas in ensuring food security and the development of the economy and population. This study focuses on the main grain-producing provinces of Jilin and Jiangsu in China. Based on county-level data on population, economy, and grain production, it constructs an index system for the population, economy, and grain systems. The study employs the entropy weighting method and coupling coordination model to analyze the coupling coordination degree and coordinated development of the three systems in Jilin and Jiangsu provinces from 2000 to 2020, covering a span of 21 years. The coupling coordination degree and coordinated development of the three systems in the main grain-producing areas have gradually moved towards high-quality coordination. In the economically underdeveloped province of Jilin, factors such as geographical environment, population size, and industrial structure impose constraints on system coordination. In the economically developed region of Jiangsu, there is a high labour force and better development of the secondary and tertiary industries, but relatively less investment in agriculture, which affects overall coordination. It is necessary to promote regions' development with high-quality coordination by leveraging their advantages in economic foundations, and further advance the construction of the main grain-producing areas. Additionally, efforts should be made to strengthen policy support for underdeveloped regions, clearly define the industrial types and positioning of counties, and focus on industrial transformation and upgrading.