Abstract: In this paper, the soil quality under different forest stands in the watershed of southern Jiangsu province from the aspect of soil fertility, biological quality and environmental quality were studied. The author took Cunninghamia lanceolata, Pinus massoniana Lamb as object, and took total nitrogen, total phosphorus, pH, MO, soil sucrase, soil urease, soil phosphatase, total Cu, total Zn, total Pb, total Cr, total Ni, etc as assessment indexes. Using the method of Fuzzy compositive assessment the soil quality were assessed. The results indicated that the compositive index of soil quality was between 0.4—0.6. The soil quality in the area belonged to the third class. The contents of phosphorus and potassium in soil made a great influence soil fertility in the area.