Grain traits have a direct impact on the yield and quality of rice. Therefore， understanding the genetic mechanism underlying these traits is crucial for improving rice yield and quality. In this study， Ludao and Guangbaixiangzhan （GBXZ）， which exhibit significant differences in grain traits， were used as parent plants to create a segregating population. Using the 1 K mGPS rice SNP chip， the targeted population was genotyped and a high-density genetic map containing 770 Bin markers was constructed. Through QTL mapping analysis， a total of 17 QTLs related grain traits were detected， including 4 QTLs for grain length， 3 QTLs for grain width， 3 QTLs for grain thickness， 2 QTLs for length-to-width ratio of grain， and 5 QTLs for 1000-grain weight. The phenotypic variation explained by these QTLs ranged from 4.73% to 29.63% with the LOD values ranging from 2.55 to 42.44. Of these 17 QTLs， 9 QTLs were known loci related to grain size， and 8 QTLs might be newly identified. Among the 8 new QTLs， qGL6 was related to grain length， qGW5， qGW10 and qGW12 were related to grain width， qGT10 was related to grain thickness， qGLWR5-2 was related to length-to-width ratio of grain， qTGW10 and qTGW11 were related to 1000-grain weight. Based on the gene annotation， Arabidopsis homologous gene comparison， spatiotemporal expression analysis， hormone response analysis， and sequence analysis of the candidate genes in the definite qGW5 region， a candidate gene Os05g0195101 encoding a CCCH-like zinc-finger protein for regulating rice grain width was finally screened. This study lays the foundation for further cloning of rice grain trait genes and analyzing the genetic regulation of grain traits.