High grain yield is one of the most important objectives in wheat breeding. Kernel number per spike (KNS) and thousand-kernel weight (TKW) are two of the three yield components of wheat, whereas there is usually a negative correlation between KNS and TKW. Therefore, combining more KNS with high TKW is essential for improving grain yield potential in wheat breeding. Spikelet number per spike (SPS) and kernel length (KL) are the major determinants of KNS and TKW, respectively. We previously mapped a major QTL for SPS and KL on chromosome arm 7AL using the recombinant inbred lines (RILs) derived from "Ning7840 × Clark", and the QTL effect has been validated in near-isogenic lines (NILs) and other mapping populations under multiple environments. In this study, we separated the QTL into two independent QTL for the two traits by screening 8167 plants of the heterozygous inbred families (HIFs) derived from the "Ning7840 × Clark" RIL population using the flanking markers. The QTL for SPS was finely mapped to an 87 kb physical interval where WAPO1 was identified as the causal gene. Further screening of the recombinants with fixed WAPO1 allele in the region identified an independent QTL for KL. Further fine-mapping of the KL QTL delimited it to an 880 kb interval. Analyses of the annotated genes in the interval and transcriptomic data of those genes identified a putative causal gene for the KL QTL, and phenotyping of EMS mutants and transgenic plants of the selected candidate gene confirmed its function in enhancing KL. Comparing the NILs carrying the contrasting alleles at the 7AL KL gene showed that the Clark allele increased KL and TKW by up to 3.5% and 5.7%, respectively. Successful identification of recombinant lines with combined superior alleles at both WAPO1 and the 7AL KL gene demonstrated the possibility of selecting large-spike wheat cultivars by breaking linkage drag to combine superior alleles for both KNS and TKW on 7AL.