Flag leaf shape is one of the most important target traits in rice ideal plant type breeding. Identification and localization of new rice flag leaf shape QTLs would be of great significance to facilitate the genetic analysis of complex traits, and provide QTLs/genes to develop new plant type rice varieties via markerassisted selection. One hundred and twenty eight chromosome segment substitution lines with 9311 as recipient and Nipponbare as donor were genotyped by wholegenome resequencing. The pairwise correlation analysis on three flag leaf shape traits was conducted. The correlations between flag leaf length and flag leaf area, and between flag leaf width and flag leaf area were significantly positive. Correlation analysis revealed that the flag leaf length and flag leaf area have a direct positive impact on spikelet number per panicle. By combining the sequencingbased Binmap with multiple linear regression analysis, four, four and six QTLs for flag leaf length, flag leaf width and flag leaf area were mapped, respectively, with contributions from 4.08% to 60.40%. The results provided a foundation for fine mapping and subsequent cloning of the QTLs.