Abstract: Based on the statistical data of Yunnan’s grain industry from 1950 to 2022, this study systematically analyzes the spatiotemporal evolution process of grain production in Yunnan, dynamically analyzes the changes in its production structure, and uses the grey correlation analysis method to quantitatively explore the influencing factors of grain production from five dimensions: production factors, technological level, natural conditions, economic conditions and social conditions. The results show that: (1) In terms of time dimension, the overall grain production in Yunnan has maintained a steady upward trend. Compared with other provinces in China, Yunnan boasts a comparative advantage in the growth rate of grain sown area. However, its grain yield growth rate has yet to achieve a comparable advantage, and the per capita grain availability remains consistently below the national average. (2) In terms of spatial dimension, the spatial differentiation characteristics of grain production in Yunnan are significant, forming a spatial pattern with eastern Yunnan (Zhaotong, Qujing) as the core and southern Yunnan (Wenshan, Honghe) and northwestern Yunnan (Dali, Lijiang) as stable supports. (3) The production structure of Yunnan’s grain production has gradually established an evolutionary path of “steady expansion of scale and deep optimization of structure”, while forming a diversified planting system with “corn as the core support, rice as the food base, and drought resistant crops such as potatoes as elastic supplements”. (4) The influencing factors are that Yunnan’s grain production is driven by both production inputs and external factors, and present a distinct primary and secondary logic, with production inputs being the core driving force for capacity improvement. Yunnan should take stabilizing the area and increasing yield per unit, strengthening division of labor and optimizing layout, adjusting structure and improving quality and efficiency, breaking through constraints with strong technology, and promoting strong economic support as key measures to ensure that the bottom line of food security is firmly held.