[Objective] The physical and chemical properties of swamp wetland in Yanchiwan National Nature Reserve of Gansu Province were evaluated to reveal the characteristics of wetland soil and the role of wetland soil in the wetland, in order to provide reference for wetland protection in the reserve. [Methods] Six typical marshes were selected in the reserve, and stratified soil samplings were collected by random method. According to the national standard, the soil porosity, soil moisture properties and soil nutrient characteristics of each marsh were measured. [Results] ① With the increase of soil depth, soil bulk density increased gradually, while soil porosity and soil aeration decreased gradually. The results of soil pore indexes in Yulin River Source Wetland and Daderji Wetland were better than those in other marshes. ② With the increase of soil depth, soil moisture properties decreased gradually. Soil moisture properties in Yulin River Source Wetland and Daderji Wetland were better than those in other marshes. ③ With the increase of soil depth, the soil nutrient contents of all marshes showed a decreasing trend. The soil nutrient contents of Yulin River Source Wetland were higher, the soil nutrient contents of Yema Daquan Wetland were the lowest, and there was no significant difference in the soil nutrient conditions of the other four marshes. [Conclusion] With the increase of soil depth, the soil of the marshes in the reserve gradually becomes compacted, the soil porosity, the water condition and the soil nutrient content decreases. The soil in Yulin River Source Wetland and Daderji Wetland are loose in quality, good in aeration, and have superior water conditions with strong ability of water storage and water conservation, while the Yema Daquan Wetland can quickly accommodate precipitation and infiltrate in time, which can effectively regulate runoff. The soil nutrient condition of Yulin River Source Wetland was the best, while that of Yema Daquan Wetland was the worst. The soil environment of the reserve marsh wetland is alkaline.