The site factors of hillsides closed to afforest in southern Shaawi Province are divided into seven types using fuzzy cluster by progressive modification from centre, including the types of thick soil, gentle slope, rich rainfall with high elevation, rich rainfall with low elevation，poor rainfall with high elev0ation, poor rainfall with low elevation and stern slo pe in order, Among the seven types, the most advantages is tim first type, then the second to the sixth, th.e poorest is the seventh, the type of si;eep slope, The results demonstrate that this kind of quantitative cluster analysis method is characterized with fast result and objective, seientiific, simple and com0enient nature when used to divide the type of site factors of hillsides closed to afforest.