Taking a sloping field of purple soil in the Three Gorges Reservoir area as an example，the authors synthetically evaluate purple soil degradation using Fuzzy model based on different landuse types and different slope segments and analyze the main driving forces leading to the degradation. Results show that vegetable land and garden are not subject to degradation;cultivated land and woodland have light degradation;grassland and wasteland have moderate degradation;construction area have severe degradation;and all the sloping fields of purple soil in different slope segments have moderate degradation. Human activities are the main factor of soil degradation in the Three Gorges Reservoir area and soil erosion is the main type of soil degradation. Natural factors such as landform,climate，parent rocks，purple soil characteristics are the conditions to soil erosion. Human factors such as severe vegetation destruction,a great many of sloping fields，and high reclamation rate，improper cultivation measure,and irrational planting system accelerate the soil deeradation in the area.