Soil salinity, exacerbated by human activities and climate change, is a growing threat to agricultural and forestry productivity. Willow known for their extensive root systems and rapid growth plays a crucial role in soil stabilization and water regulation. This study investigates the Rab GTPase family in S. matsudana, which is vital for intracellular vesicular trafficking and plant responses to salt stress. We identified 120 SmRabs in S. matsudana, revealing a wide range of physicochemical properties. Phylogenetic analysis categorized these into eight clades (RabA-H), with RabA being the most populous. Duplication events were discovered, with 182 syntenic SmRab pairs, suggesting whole-genome or segmental duplications. Ka/Ks ratios indicated purifying selection, with a few exceptions suggesting positive selection. Quantitative real-time PCR analysis revealed differential expression of SmRabs under salt stresses, suggesting their roles in stress response. Heterologous expression of SmRabD2g in yeast enhanced salt tolerance, indicating a protective role. Arabidopsis transformation with SmRabD2g construct showed improved salt tolerance, with transgenic plants exhibiting reduced damage under salt stress. This comprehensive study provides insights into the evolutionary dynamics and functional roles of SmRabs in S. matsudana, offering potential for genetic engineering to enhance salt tolerance in willows, contributing to sustainable production in saline soils.