In order to optimize the distribution of grain production industry and ensure food security, the refined agro-climatic zoning of wheat and corn planting in Zhongjiang was carried out based on GIS. This paper used the daily meteorological data of Zhongjiang Meteorological Monitoring Station from 2007 to 2016, and the meteorological data of the sunshine duration, temperature and precipitation of the 30 automatic stations in and around the Zhongjiang from 2011 to 2015, 2007-2016 wheat and corn sown area, total yield and unit yield, as well as 1:250000 geographic information data and digital maps to compare the difference between the high yield years and poor yield years through analyzing the direct relationship between the meteorological yield of wheat and corn and the meteorological conditions in each growth period in Zhongjiang and its surrounding areas. Three key growth periods and six key climate factors of corn and wheat were selected as the regionalization indicators for the zoning of main grain crops in Zhongjiang County. The results show that Gudian, Shiquan, Jifeng, Fuxing, Nanhua, Dongbei, some parts of Yongxing Town and Shisun Township in the south, and the southernmost Yuanxing and Yongfeng Township are basically suitable because of their high terrain and poor water supply, while the rest are more suitable. We can make use of the advantages of climate resources and soil resources in these suitable areas to actively develop the cultivation of food crops to ensure food security.