【Objective】This study aimed to elucidate the mechanism by which sorbitol-chelated potassium (SK) promoted nutrient uptake and utilization in wheat leaves.【Method】In this study, sorbitol-chelated potassium was used as the test foliar fertilizer and wheat cultivar Tainong 108 as the experimental material to elucidate the effects of foliar application of different potassium forms on leaf physiological and biochemical traits as well as phyllosphere microbial community structure. Structural equation modeling (SEM) was further employed to quantify the contribution of each factor to wheat yield, thereby providing a theoretical basis for the yield-enhancing mechanisms of chelated potassium fertilizers.【Result】Results from two consecutive field seasons showed that, compared with potassium chloride (K) and a mixture of sorbitol and potassium chloride (S+K), the SK treatment significantly affected wheat leaf physiological and biochemical characteristics and bacterial richness. (1) Mean yield increases were 24.74% and 18.76%, respectively. (2) Grain Mn concentration increased by 16.14% and 12.12%, grain K by 45.68% and 21.96%, late grain-filling stage leaf K by 81.01% and 24.44%, and maturity satge leaf C by 2.52% and 1.95%. (3) Activities of catalase, peroxidase and superoxide dismutase were better maintained, while malondialdehyde content decreased by 25.65% and 7.51%; the activities of protein synthesis enzymes (nitrate reductase, glutamine synthetase and glutamate-pyruvate transaminase) were sustained during mid-to-late grain filling satge. (4) Relative abundance of Firmicutes rose by 57.36% and 50.00%, whereas Actinobacteria declined by 21.63% and 4.26% and Cyanobacteria by 36.05% and 62.03%.【Conclusion】SK treatment enhanced yield and grain quality through the synergistic regulation of wheat leaf element content, antioxidant capacity and protein synthesis enzyme activities. SEM further demonstrated that all measured indicators were directly or indirectly linked to final grain yield.