Tiller angle (TA), influencing photosynthetic efficiency, stress resistance and grain yield greatly, is an important component of wheat plant architecture. Two hundred and sixty-six recombinant inbred lines (RILs) derived from a cross between Zhongmai 871 (ZM871) and its sister line Zhongmai 895 (ZM895) were evaluated for TA in eight environments during 2015-2017 cropping seasons, and genotyped by the wheat 660K SNP array, to identify TA genes and closely linked molecular markers. Two quantitative trait loci (QTL) on chromosomes 1AL and 5DL were mapped by inclusive composite interval mapping with the alleles for reducing tiller angles from ZM895. QTA.caas-1AL was detected in six environments, explaining 5.4-11.2 % of the phenotypic variances; while QTA.caas-5DL, a major stable QTL, was identified in all eight environments, accounting for 13.8-24.8 % of the phenotypic variances. These two QTL were further validated using BC1F4 populations derived from backcrosses ZM871/ZM895//ZM871 (121 lines) and ZM871/ZM895//ZM895 (175 lines). TraesCS5D02G322600, an ortholog of rice TA gene OsTAC1, is located in the QTA.caas-5DL region, designated as TaTAC-D1. Sequence analysis of TaTAC-D1 revealed a SNP in the third exon with ‘A’ and ‘G’ in ZM871 and ZM895, respectively, resulting in a Thr169Ala amino acid change. A KASP marker, designated as KASP-TAC-D1, was developed to discriminate the two alleles and validated in two sets of wheat cultivars, in which less than 30% of the 156 and 93 cultivars had the TaTAC-D1-G allele that exhibited significantly smaller TA than those with the TaTAC-D1-A allele. Near-isogenic lines of TaTAC-D1, NIL871 and NIL895 with homozygous alleles from ZM871 and ZM895, respectively, were constructed with a residual heterozygous line in the ZM871/ZM895 RIL population. It indicated that NIL895 had a significantly (P < 0.05) smaller TA than NIL871 regardless of irrigation status, but a significantly (P < 0.05) higher spike number per square meter (SNSM) and grain yield (GY) than NIL871 under the full irrigation condition, whereas no significant difference on SNSM and GY was observed in the reduced irrigation condition, and no significant differences in plant height, grain number per spike and thousand grain weight between NIL871 and NIL895 were detected in both the full and reduced irrigation conditions. The present study provides important genes and molecular markers for improvement of wheat yield in breeding programs.