Abstract: In this study, two kinds of leguminous plant, soybean and trigonella foenum-graecum, were imported in monoculture greenhouse. The effects on soil microbial biomass N, microbial biomass C, soil microbial biomass, and soil enzyme activity were investigated before/after green manure returned to field. The results showed that in the fallow period of greenhouse, the enzyme activities of cellulase, urease, sucrase, significantly increased after planting soybean and trigonella foenum-graecum. Compared with planting trigonella foenum-graecum, the amount of dry matter was highter in soybean planted treatment. After green manure returned to field, the soil enzyme activities in soybean treatment were lower than those in trigonella foenum-graecum, but the soil microbial population, population and ratio of bacterial, soil microbial biomass N and C were significantly higher than those in trigonella foenum-graecum and control, and microbial biomass C/N was more optimum. In conclusion, soybean could be used as short-term green manure crop in greenhouse.