Digital transformation is conducive to food security. This paper constructed an index system of the digitization level of the grain industry chain based on the panel data of 30 provinces in China from 2011 to 2022. It adopted the entropy method to measure it and analyzed the law of its spatial–temporal evolution. It was found that the digitization level of China’s grain industry chain has shown a year-on-year growth trend, and, at the same time, there are spatial spillover effects and spatial heterogeneity. Analyzed by Theil’s index, there were evident differences among the four major regions and three major grain functional areas in China, and the differences mainly originated from within the region, and there was a phenomenon of “digital divide”. The digitalization level of China’s grain industry chain has shown a decreasing trend of “East-Middle-West”. In conclusion, this paper proposes practical countermeasures to facilitate the digitization level of the grain industry chain in China, thereby providing developing countries with a reference value for the digital transformation of the grain industry chain. Therefore, we should promote the construction of digital infrastructure, increase the cultivation of digital talents, coordinate regional development, and accelerate the digital transformation of the grain industry chain.