The tiller angle is one of the most important traits in the plant architecture of rice， which significantly determines the rice yield. At present， the major tiller angle genes in rice are TAC1 （Tiller Angle Control 1） and TIG1 （Tiller Inclided Growth 1）. It is necessary to further explore new loci and molecular markers to promote ideal plant architecture breeding in rice. In this study， a BC₃F₂ population was developed using large-angled wild rice as the donor and small-angled cultivar Zhenshan 97 as the recipient， and tiller angle separation was observed in the 54th line. QTL mapping of tiller angel was performed using QTL-seq， and a QTL was detected on chromosome 8. TIG1 was identified as the candidate gene through sequence comparison of known genes within the interval. A KASP functional molecular marker was designed based on the causal variation of C?T at -449 bp in the promoter of TIG1. The marker was verified in the mapping population and varieties， and it was confirmed that the KASP marker can accurately identify the genotype of the TIG1 locus. In Geng/Japonica TIG1 with large angle is dominant， while 61.40% and 38.40% of Xian/Indica varieties carry tig1 with small angle and TIG1 with large angle， respectively. This marker has significant potential utilization value for improvement of rice plant architecture. The development of this KASP marker provides a new tool for molecular marker-assisted improvement of rice tiller angle and is expected to speed up the breeding process for the ideal rice plant architecture.