According to the basic principles and methods of environmental economics, the value losses caused by soil erosion in Nanchong City were analyzed and estimated. The comparison of the result with the main index of economic construction was used to indicate directly the extent of the economic cost resulting from soil erosion. Results showed that the total value loss by soil erosion was 621586 300 Yuan in 2002, being 4.96% of agricultural GDP of the year. The value loss by nutrient losses, mainly including N, P, K, was 549 804 200 Yuan, being 88.45% of the total value loss by soil erosion. The economic value loss by soil erosion in Nanbu and Langzhong districts was most serious in Nanchong City.