Abstract: The pepper straw was used as the test material, and the ITS sequence of soil fungi was analyzed by high-throughput sequencing.The effects of in-situ returning of greenhouse vegetable straw on soil fungal community structure were studied, in order to clarify the response of soil ecological community structure to vegetable straw returning.Three treatments were set up, no straw returning（CK）,straw returning（NK） and straw returning with microbial agent（TJ）.The soil water-soluble organic carbon, nitrate nitrogen, ammonium nitrogen, available potassium and soil fungal community structure were measured.The results showed that compared with the soil before the greenhouse, straw returning and adding microbial agents significantly increased the electrical conductivity, and the contents of soil water-soluble organic carbon, nitrate nitrogen, ammonium nitrogen and available potassium increased by 58.25%,219.50%,34.59% and 101.70%,respectively.Straw returning changed the composition of soil fungal community.Compared with no straw returning, straw returning increased the relative abundance of Ascomycota by 9.17% and decreased the relative abundance of Mortierella by 0.17%.However, the relative abundance of the dominant genus Mortierella was significantly reduced by 8.29% compared with that before the greenhouse.The order of influence of soil physical and chemical factors on fungal community diversity in all samples was nitrate nitrogen＞ammonium nitrogen＞available phosphorus＞EC value＞pH＞water-soluble organic carbon＞available potassium.Straw returning of greenhouse vegetables significantly increased the contents of water-soluble organic carbon, nitrate nitrogen, ammonium nitrogen and available potassium in soil, and the increase was more significant in the treatment of straw returning with decomposition agent.The in-situ returning of vegetable straw changed the composition of fungal community, but did not increase the content of pathogenic bacteria, and there were no pests and diseases in the process of plant growth, indicating that the combination of in-situ returning of straw and greenhouse was a scientific agronomic measure.