Rice is one of the most important cereal crops in China. Plant height and grain type are crucial factors determining rice yield. Exploring the genes regulating plant height and grain type is of great significance for improving rice productivity. In this study, a dwarf and small grain mutant was screened from the progeny of EMS-induced mutations in the rice variety Jida 718, and it was named dwarf and small grain-JD718（dsg-j）. Compared to the wildtype, the mutant exhibited reduced plant height, smaller grains, and decreased thousand-grain weight. Observation of stem internode sections confirmed that the dwarf phenotype was caused by decreased cell size in the mutant. Genetic analysis revealed that the mutant phenotype was controlled by a single recessive gene. Further analysis using BSA-Seq technique preliminarily mapped the dsg-j gene to the seventh chromosome. This study laid the foundation for cloning and functional analysis of the dsg-j gene, providing clues for further elucidation of the molecular mechanisms underlying plant height and grain type regulation.