This study aimed to investigate the effects of compound substrates formulated with grapevine pruned canes on the rhizosphere microenvironment，yield，and quality of greenhouse-cultivated pepper plants，thereby providing a theoretical foundation for the sustainable utilization of viticulture waste.Using pepper (Capsicum annuum L.) cultivar ‘Longjiao No.6’ as the experimental material，four compound substrates were formulated by mixing composted waste grape branches，peat，and perlite at the following volume ratios:20∶50∶30 (T1)，30∶40∶30 (T2)，40∶30∶30 (T3)，and 50∶20∶30 (T4)，and a commercial substrate served as the control (CK).The nutrient composition and enzymatic activities of the substrates，alongside the rhizosphere microbial diversity，pepper quality，and yield were comparatively analyzed.Compared to CK，treatments T1，T2，and T4 exhibited significant increases in available nitrogen，phosphorus，and potassium by 13%-51%，15%-28%，and 10%-15%，respectively.All treatments showed notably higher enzyme activities than CK，with T4 demonstrating marked enhancements in alkaline phosphatase and urease activities.However，total nitrogen and total phosphorus content in the compound substrates decreased.The bacterial community richness and diversity in the rhizosphere of pepper plants grown in compound substrates were elevated compared to CK，accompanied by increased relative abundances of Actinobacteria and Myxococcota.Redundancy analysis revealed that pH and C/N were key drivers of bacterial community structural shifts.Additionally，T3 treatment displayed superior root vigor，root volume，and fruit quality traits (e.g.，vitamin C，soluble sugars，and soluble solids).T3 achieved the highest yield (71920.5 kg·hm-2)，with a benefit-to-cost ratio of 2.43 and a net profit of 169500 Yuan·hm-2.Based on a comprehensive analysis of rhizosphere substrate nutrients，enzyme activity，microbial diversity，fruit quality，and yield，the treatments were ranked by overall performance as T3>T4>T2>T1>CK.The optimal substrate for pepper cultivation was identified as T3 (fermented grapevine canes :peat :perlite = 40∶30∶30)，demonstrating superior integrated agronomic benefits.