Abstract: 【Objective】To clarify the influence of suitable soil environment and growth process of medicinal plants on soil structure in desert steppe area. 【Methods】Taking the growing soil of Sophora alopecuroides L. ,Manc hurian hancock (Maxim)Al. and Dracocephalum moldawica L. as the research object in the desert steppe area ,the soil available nutrients ,pH, soil particle size and fractal dimensions and their correlation were analyzed.【Results】The pH of the growing soil of the three medicinal plants Sophora alopec uroides L. , Manchurian hancock (Maxim.)Al. and Dracocephalum moldawica L. was 9.11-10.35,the content of alkali hydrolyzed nitrogen was 5.13,2.37,7.10 mg/kg , the content of available phosphorus was 3.05,6.74,3.13 mg/kg, and the content of available potassium was 114.52,117.48, 181.69 mg/kg;sand content was 83.41%,87.29% ,84.77% ,respectively. The growth soil particle size curve of various medicinal plants were bimodal ,and the growth soil of Manchurian hancock (Maxim.)AI. had the highest value at 1 000 μm. The 0-10 cm soil layer had better soil uniformity for the growth of Manc hurian hancock (Maxim.)Al. and the soil uniformity for the growth of Dracocephalum moldwicaL. 10- 20 cm and 20 -30 cm soil layer was better. 【Conclusion】Sophora alopecuroides L,Manchurian hancock (Maxim)AL,and Dracocephalum moldaw ica L. are suitable for growth in alkaline soil environment ,sandy soil, higher soil available potassium content, and the content of other available nutrients is lower than the appropriate level. Manchurian hancock (Maxim.)Al. grows with coarse soil particles. The soil particles has a tendency of coarsening and there is a threat of further desertification.

Key words: Desert steppe, Medicinal plant, Soil particle size, Soil nutrients