Abstract: Exploring the effects of the application of compound microbial cultures on the growth and leaf enzyme activity of Astragalus membranaceus seedlings,providing a theoretical basis for the efficient utilization of compound microbial cultures.The triple quadratic regression orthogonal rotation combination design (1/2 implementation) was used to study Enterobacter aerogenes (CT-B09-2) and Bacillus amyloliquefaciens (JL-B06) and Acinetobacter calcoaceticus (WYS-A01-1) were combined to treat A.membranaceus,and root biomass and leaf metabolic enzyme activity were measured in Fujian Agriculture and Forestry University in 2023.The application dosage of three strains was used as independent variable X,and the activity of A.membranaceus peroxidase POD enzyme,soluble sugar content and root dry weight were used as dependent variable Y.The regression fitting equation Y₁=28137.76638+4900.32338X₁+4030.94814X²₁+5053.45778X²₂-4676.49614X₁X₃-7967.51338X₂X₃;Y₂=0.14161+0.00709X₁+0.01204X₂-0.00879X₃-0.00332X²₃+0.00917X₁X₂-0.01243X₁X₃-0.00771X₂X₃;Y₃=0.81502+0.10808X₂+0.02865X₃-0.05351X²₁+0.01177X²₂-0.02479X²₃-0.14615X₁X₂-0.21408X₁X₃+0.10884X₂X₃.The results showed that POD enzyme activity,soluble sugar content and root dry weight changed with the combined application of the three strains.The mixed application of the three endogenous growth promoting bacteria could significantly promote the growth of A.membranaceus and improve the metabolic enzyme activity of leaves,and the treatment group 8 (Enterobacter aerogenes:Bacillus amyloliquefaciens:Acinetobacter calcoaceticus=40 mL∶80 mL∶40 mL) works best.