Abstract:Abstract: Yan'an City is located on the loss plateau of Northern Shaanxi Province with severe water and soil erosion problem and poor condition of agricultural production. Water resource shortage and soil erosion have been two of the most important factors that limit the sustainable agricultural development. This study aimed to investigate the spatial matching pattern and carrying capacity of agricultural water and soil resources in Yan'an City. The water-and-soil resources relevant data from 2003 to 2013 were collected. An available water resource was employed to represent water resources. Then the Gini coefficient method based on the Lorenz curve and a model for calculating matching coefficients were constructed to evaluate the matching degree of agricultural water and soil resources of Yan'an City and its 13 administration counties. Additionally, by studying the factors affecting carrying capacity of agricultural water and soil resources, an evaluation system consisted of a target layer, a system layer and an index layer was established. Meanwhile, the Particle Swarm Optimization was adopted to optimize the projection index function and determine the one-dimensional value, and a Projection Pursuit Classification model was constructed to evaluate the agricultural water and soil resources carrying capacity at Yan'an City. The results showed that the Gini coefficient of water and soil resource in Yan'an City was 0.449, indicating the poor matching degree. The matching coefficient of agricultural water and soil resources in Yan'an City was 0.26×104 m3/hm2, which was below average level of Shaanxi Province (0.47×104m3/hm2) and far below the national average level (0.54×104m3/hm2), indicating a poor matching degree as well. The spatial matching pattern of the water and soil resources suggested that the matching degree was higher in South than that in North. Meanwhile, the agricultural water and soil resources carrying capacity of the administration counties in Yan'an City was different greatly, being lowest in Zichang and Yanchang (belonging to the IV level), indicating severe imbalance between socioeconomic development and water-soil resources development in these cities. The carrying capacity of Huanglong County was the highest, which belonged to the II level and indicated that the water-soil resources could satisfy the socioeconomic development, and the carrying capacity of other counties belonged to the III level and presented an imbalance development between social economy and water-soil resources. From this study, it suggested that the water diversion project and the farmland infrastructure project should be made and carried out to improve the basic conditions of agricultural production in these counties of Yan'an.