Abstract: Long-term return of straw to the field can provide rich nutrients for paddy soil. The effects of different straw return amounts on the physicochemical properties and fungal diversity of rice soil were discussed, and this paper provided scientific basis for the rational utilization of rice straw. In 2014, a straw returning field positioning experiment was conducted in Longmen Town, Mianyang, Sichuan. Set up four different treatment methods, S0, S1, S2, and S3, and collect 0-20cm soil samples after rice harvest for fungal community structure analysis and soil nutrient determination. Compared with S0, there was no difference in pH between different treatments. The content of total phosphorus, available phosphorus and ammonium nitrogen increased. Compared with S0, the available phosphorus content increased by 40.65%, 62.68% and 90.38%, respectively. The total phosphorus content increased by 8.07%, 13.55% and 22.91%, respectively. The contents of ammonium nitrogen increased by 7.70%, 9.63% and 11.56%, respectively. Compared with straw return, other straw return treatments significantly improved the Chao1 index and ACE index of fungi. Principal component analysis showed that straw treatment significantly changed the fungal community structure. In terms of community composition, the relative abundance of microcystic bacteria and fecal fungi in soil after straw return increased significantly compared with 50 treatment, increasing by 8.11%～25.31% and 21.63%～39.23%, respectively. Compared with S0 treatment, the abundance of L. stones was significantly reduced by 44.92%～48.25%. Redundancy analysis indicates that fungal communities are mainly affected by total phosphorus, available phosphorus, and nitrate nitrogen. This study indicates that by adding appropriate amounts of straw, the content of total phosphorus, available phosphorus, and other nutrients in the soil is significantly increased. Returning straw to the field caused changes in the fungal community structure of paddy soil. RDA and correlation analysis showed that total phosphorus, available phosphorus, and nitrate nitrogen had a significant impact on the fungal community structure.