Abstract: To understand the effect of different fertility treatments on soil microbial properties of Paulownia fortunei plantations, the change of soil enzyme activity, soil microbial biomass, and the correlations among soil microbial biomass, soil enzymes, and chemical index of 4-year-old P.fortunei plantations were analyzed with principal components under 4 different fertility treatments. Result showed that this 3 different fertilizer significantly increased the activity of soil catalase, urease, acid phosphatase and invertase. Urease, acid phosphatase and invertase increased more significantly under SF than other treatment respectively by 79.01%, 72.40% and 230.76% which compared with the control group with no fertilizer. 3 different fertilizer significantly increased the soil microbial biomass. Compared with the control group, soil microbial biomass carbon and nitrogen increased more significantly by 321.02% and 386.87% under SF. Except for pH, soil nutrient and soil enzyme activity appear positive correlation under SF. Soil microbial biomass carbon, nitrogen and phosphorus had positive correlation with soil enzyme activity, soil microbial biomass carbon, nitrogen and phosphorus had positive correlation with soil nutrient. The specific fertilizer has the largest impact on soil microbial activity and chemical indicators.