【Objective】Soil salt stress is one of the major abiotic stresses that severely inhibits plant growth, development and productivity. Elucidating the molecular regulatory mechanisms of plant responses to salt stress is of great theoretical and practical significance for breeding stress-resistant forest trees and promoting their genetic improvement. In this study, ‘84K’ poplar (Populus alba × P. glandulosa ‘84K’), a widely used model tree in genetic research, was used as the experimental material. The structural and evolutionary characteristics of the bZIP transcription factor gene family were systematically identified and analyzed, and the biological function and molecular regulatory mechanism of PagbZIP36 in response to salt stress were further explored, aiming to provide reliable gene resources and theoretical support for molecular breeding of stress-resistant forest trees.【Method】A comprehensive bioinformatics analysis was performed to characterize the gene structure, phylogenetic relationships, conserved motifs and promoter cis-elements of the bZIP gene family. The expression pattern of PagbZIP36 under salt treatment was detected, and its salt tolerance function was identified through phenotypic observation and physiological index determination in transgenic poplar. In addition, DAP-seq combined with molecular biology experiments was used to verify the regulatory relationship between PagbZIP36 and its downstream target gene PagGolS2 during salt stress response.【Result】A total of 190 bZIP family members were identified from the ‘84K’ poplar genome and were divided into 13 distinct subfamilies. PagbZIP36, a member of the S subfamily, contained 70.1% salt stress-related cis-acting elements in its promoter region and was significantly induced by salt stress. Overexpression of PagbZIP36 significantly enhanced salt tolerance in transgenic ‘84K’ poplar. Further mechanistic analysis indicated that this transcription factor regulates the expression of the downstream functional gene PagGolS2, enhances reactive oxygen species scavenging efficiency, maintains cell membrane stability, effectively alleviates oxidative damage caused by high salt, and ultimately improves poplar salt tolerance.【Conclusion】Members of the bZIP S subfamily exert pivotal roles in plant salt stress response and tolerance. Among these regulators, PagbZIP36 enhances reactive oxygen species scavenging capacity and maintains cell membrane stability by targeting and modulating the expression of PagGolS2, thereby conferring significantly elevated salt tolerance in forest trees. This study provides critical candidate genes and a robust theoretical foundation for molecular breeding programs aimed at improving stress resistance in forest trees.