Abstract: Through mixing two kinds of neutral salts（NaCl and Na₂SO₄） and two kinds of alkaline salts（NaHCO₃ and Na₂CO₃）,different intensities of salt and alkali stress conditions were simulated respectively,and garden plants were treated with stress for 3 years（2015—2017） to explore the effects of salt and alkali stress on soil enzyme activity and microorganisms of garden plants.The results showed that,1) the organic acid content in soil decreased gradually with the increase of saline-alkali concentration.With the increase of stress intensity,the concentration of Na⁺ in soil increased significantly under salt and alkali stress,and decreased significantly under K⁺ stress.2) With the increase of salt concentration,soil amino acids,carbohydrates,carboxylic acids,polymers,amine and phenolic acids gradually reduced.Meanwhile,carbohydrates and carboxylic acid type of carbon source were main carbon source of soil microorganisms of garden plants under salinity stress,followed by amino acids,phenolic acids and polymer,amine carbon source utilization rate was minimal.3) Soil microbial species richness index（H）,evenness index（E） and carbon source utilization richness index（S） gradually reduced.4) Soil glycosidase,chitinase,leucine aminopeptidase,alkaline phosphatase,δ phenol oxidase and δ peroxidase decreased sharply.5) The interaction analysis showed that salt stress,alkali stress,salt stress by alkali stress on organic acids,Na⁺,K⁺,Na⁺/K⁺,species richness index（H）,carbon source utilization richness index（S）,soil microbial biomass carbon,soil microbial respiration,soil microbial metabolism entropy,glycosidase had significant effect and alkaline phosphatase（P＜0.05）,in which the alkali stress on the influence of soil enzyme activities and microbial community diversity was higher than the influence of salt stress,and the effects of salt stress by alkali stress was higher than the single salt stress or alkali stress.