In recent years, with the implementation of grain safety engineering and high-quality grain engineering, grain storage enterprises have carried out research and application of multiple green grain storage technologies such as air conditioning temperature control, grain cooling temperature control and humidity control, internal circulation moisture and temperature control, controlled atmosphere, and comprehensive pest and mold prevention and control based on different regional climate conditions and the storage variety, storage scale, and enterprises processing. These efforts have effectively improved the level of grain storage safety guarantee in China. The safety of grain storage is closely related to moisture content. High moisture content in the grain may cause mold growth or even hotspots, which can endanger the safety of grain storage. On the other hand, low moisture may affect the quality of food consumption and processing. Thus, it is crucial to establish a scientifically and reasonably determined safe storage moisture content of grain under the premise of ensuring the safety of grain storage. This will effectively promote the “green warehousing improvement action” and help save grain to reduce losses. This paper focused on the research process of grain safe storage of moisture in China after more than a decade of research and expert argumentation, key indicators and detection methods that affect the safe storage of grain moisture have been determined, as well as the criteria for determining the safe storage of grain moisture content, in combination with the actual storage situation at home and abroad. Research on the safe storage of grain moisture content in conventional storage and temperature-controlled storage has been systematically carried out, and the relationships between grain moisture content and temperature have been established. The threshold for safe storage of grain moisture content in the region under the new situation has been proposed, which could provide technological support for the formulation of green grain storage related standards.