Abstract: In order to evaluate the soil fertility of the North-west of Hu’nan province, based the 371 soil samples of the representative locations of Longshan and Fenghuang counties. The data was done with member function and the weights of soil nutrients were definited with principal component analysis by means of estimating SFI to evaluate the soil fertility. The results indicated that: (1) The organic matter content in the north-west of Hu’nan tobacco-growing areas was suitable; pH was partial low; The macro elements of nitrogen, phosphorus potassium content were abundant; But the hydrolytic nitrogen content was on the high side; The secondary elements of exchangeable calcium and magnesium and the available sulfur content were appropriate; The microelements of available zinc, copper, iron, molybdenum content were rich, but the available boron content was deficient and the available manganese was high. (2) The SFI ranged from 0.17 to 0.76 with the mean of 0.57 and coefficient variation of 15.11%. (3) The soil fertility was classified into 5 groups of higher, high, medium, low and lower based on the SFI, and SFI was in the extent of 0.2 ~0.6 for 64.69% of the soil samples.