As the three main grains in China, rice/paddy, wheat and corn play an important role in the food structure of Chinese residents. Quality monitoring is an indispensable and important link in the industrial chain of grain production, processing, storage and transportation. In particular, efficient, nondestructive, objective and real-time optical quality detection is of great significance to the healthy development of the grain industry. Firstly, the optical characteristics of visible/near-infrared spectrum, Raman spectrum and fluorescence spectrum of three main grains as well as the optical detection mechanism of internal quality were compared and analyzed. The application and research status of optical detection technology for internal quality of grain at home and abroad was summarized and analyzed. The application scope and research status of machine vision, hyperspectral and other grain appearance quality detection technologies was discussed. Secondly, combined with the specific quality detection needs of the three main grains, the research and development status of optical detection devices for grain internal quality at home and abroad was summarized and analyzed. The research status of hardware composition and spatial arrangement of appearance quality detection devices was emphatically discussed, and the commercialization and application of optical detection technology related devices were analyzed. Finally, from the bottleneck of optical detection technology of grain quality, the problems and development trend of fast optical detection technology and its equipment were prospected.