Abstract: Due to the non-agricultural use of land and high population concentration, ensuring grain security in urban agglomerations is of great significance for the stable socio-economic development. Based on data from 229 prefecture-level cities in 17 urban agglomerations in China from 2000 to 2022, this study calculates the grain supply-demand gap and its link to grain flow potential, and classifies urban agglomeration grain security types into four categories using kernel density analysis and standard deviation ellipse methods. The study indicates that: 1) In 2022, the grain security capacity of 17 urban agglomerations ranked from strongest to weakest as follows: Harbin-Changchun, Central Plains, Hohhot-Baotou-Ordos-Yulin, Beijing-Tianjin-Hebei, Middle Yangtze, Chengdu-Chongqing, Shandong Peninsula, Guanzhong Plain, Central-Southern Liaoning, Central Yunnan, Central Shanxi, Central Guizhou, Lanxi, Beibu Gulf, Yangtze River Delta, West Coast of the Taiwan Strait, and Pearl River Delta urban agglomerations; 2) Chongqing in the Chengdu-Chongqing urban agglomeration and Harbin in the Harbin-Changchun urban agglomeration, influenced by factors such as natural resource endowment, have become the main cities supplying grain in their respective urban agglomerations; And 3) In other urban agglomerations, under the influence of population spatial concentration and industrial restructuring, the grain supply areas are shifting toward the periphery. The Beijing-Tianjin-Hebei, Guanzhong Plain, Central Yunnan, Central Guizhou, and Central Shanxi urban agglomerations exhibit a single-center concentric structure; the Middle Yangtze, Pearl River Delta, Lanxi, and Hohhot-Baotou-Ordos-Yulin urban agglomerations display a multi-center concentric structure; while the Yangtze River Delta, Shandong Peninsula, Beibu Gulf, West Coast of the Taiwan Strait, Central-Southern Liaoning, and Central Plains urban agglomerations show a belt-like concentric structure. Accordingly, for the four types of urban agglomerations, a grain security governance system adapted to the spatial structure should be established through differentiated grain industry layouts, optimized circulation systems, and interregional collaboration mechanisms.