Growth and dormancy are the two most important biological processes in the life cycle of perennial plants. Studying dormancy-related traits is of great significance for understanding the adaptability of forest growth and improving the efficiency of plant molecular breeding. In order to reveal the genetic mechanism of poplar bud set, we performed quantitative trait locus (QTL) locating analysis of the trait with the KW method in the software MapQTL, based on the F₁ hybrid population derived from a cross of Populus deltoides and Populus simonii and the two parental linkage maps. As a result, 15 QTLs controlling bud set were identified distributing on 7 linkage groups, among which 12 QTLs were located in linkage groups LG-1, LG-7, LG-9, LG-11 and LG-15 on the maternal P. deltoides map, whereas the other 3 QTLs were distributed in linkage groups LG-9 and LG-12 on the paternal P. simonii map. According to the location of the QTLs on the P. trichocarpa genome, a total of 45 candidate genes for bud set were identified. Furthermore, GO and KEGG enrichment analyses revealed that 71% of the candidate genes possessed potential functions in light and hormone signal transduction pathways. The research results provide a valuable resource for exploring the genes involved with bud set in poplar and for the application in molecular marker-assisted breeding.