Abstract: Rice is one of the important cereal crops in the world, and its yield and quality have always been the focus of breeders, which are related to global food security and human health. Rice grain type, mainly includes grain length, grain width and grain thickness, is an important quantitative trait controlled by multiple genes, and it not only directly affects rice yield, but is also closely related to rice quality. A good understanding of the formation and regulation mechanism of grain type will help to further increase rice yield per plant and improve rice quality. The development of molecular biology and the study of genomics have brought new changes to the exploration of the internal regulation mechanism of rice. A large number of quantitative trait locus (QTL) of rice grain type have been successfully identified and analyzed, and the functions of genes related to them have been verified. So far, several pathways regulating grain type have been identified, such as ubiquitin-proteasome degradation pathway, G protein signaling pathway, mitogen-activated protein kinase (MAPK) pathway, transcription factor regulation pathway, plant hormone pathway and MiRNA-related pathways. However, the regulatory network of grain type is extremely complex, and the mechanisms of the upstream and downstream regulatory components of many genes are still unclear, and there are even some cross interactions among the pathways that affect grain type. This review discussed the research progress of genes related to different signaling pathways affecting rice grain type and the interaction between key grain type genes, summarized the application of grain type genes in breeding in recent years, and proposed to analyze the regulation mechanism of rice grain type with multi-omics, with an aim to better serve the molecular design and breeding and provide support for the development of new high-yield and high-quality rice breeding.