Abstract: Grain-weight is a major determinant factor of rice yield. We summarized the current status of large-grain rice germplasm resources and recent progress in genetic analysis of grain-weight genes. Grain-weight is a complex quantitative trait controlled by multi-genes. So far, 89 QTLs for grain-weight have been identified. A grain-weight gene gw3.1 and a grain-length gene Lk-4(t) have been fine-mapped and a grain-weight gene GS3 has been isolated. The breeding applications of grain-weight gene in rice are also discussed.