In order to construct a comprehensive evaluation index system of agricultural water and soil resources carrying capacity, this paper selected 20 indexes from four system layers of water resources, society, economy and ecological environment. Then we analyzed the comprehensive carrying capacity of water and soil resources in each region of Ningxia irrigation area in 2015 using the PSO-PPE model based on the particle swarm optimization. The result showed that the overall level of soil and water resources carrying capacity of Ningxia irrigation area is relatively low. The evaluation value of carrying capacity of multiple districts is less than 2 including Hongsibao and Guhai, with the rating grade only Ⅳ. Even the best projection index values of the four partitions in grade Ⅲ are also low (the highest value was 2.809). According to the evaluation results of the four systems, the main influencing factors of soil and water resource carrying capacity are different in different regions. Therefore, we should take into account the actual characteristics of water and soil resources in different regions, as well as the utilization of water resources, ecological maintenance of water resources and external support of social economy, and then formulate scientific and reasonable measures, for the management and utilization of water and soil resources, and to improve the bearing capacity of water and soil resources in the irrigated area.