The tiller angle is one of the most important traits in the plant architecture of rice, which has a significant impact on rice yield. We developed a BC3F2 populations with wild rice as the donor parent and cultivar zhenshan 97 as the recurrent parent. With QTL-seq we detected a QTL on chromosome 8 in line LHY54. After comparing the sequence of cloned gene in this region, TIG1 (TILLER INCLIDED GROWTH 1) was chosen as the candidate gene. In this study, a KASP molecular marker was designed based on the variation of the -449 bp C?T in the promoter of TIG1 gene. The marker was validated in the mapping population and cultivars, which is an efficient functional marker. TIG1 is fixed as strong functional TIG1 allele in Geng/japonica (C at - 449bp of promoter) but is largely divergent in Xian/indica. The development of this functional KASP marker would improve the efficiency of conventional rice plant architecture breeding via marker-assisted selection.