With soda saline-alkali paddy soil as the test soil, 5 treatments of 0, 3.0, 7.5, 12.0, 16.5 t /hm² were set to investigate the effects of continuous biochar returning on nutrients of soda saline-Alkali paddy soil and fungal community structure through pot experiment. The results showed that: (1) The soil pH, organic matter, available potassium, available phosphorus and total phosphorus were increased and the total nitrogen and total potassium showed a trend of increasing at first and then decreasing with the different amounts of biochar returning, which amended the saline-alkali soil. (2) Illumina MiSeq sequencing results showed that relative abundance of Aphelidiomycota, Basidiomycota and Alternaria under 7.5 t/hm² was significantly higher than that of control and the relative abundance of Ascomycota, Mucoromycota and Mortierella under 12.0 t/hm²was significantly higher than that of control. Correlation analysis indicated that soil physicochemical characteristics were closely related to the relative abundance of fungal phyla and genus, suggesting that biochar affected the relative abundance of fungi by regulating the physicochemical properties of soil. (3) Biochar returning treatment had little influence on fungal α diversity, while had a certain impact on the structure of soil fungal community, especially at a higher biochar returning level. Redundancy analysis (RDA) that further analyzed the environmental factors affecting the change of community structure, indicated that the total potassium content had the greatest impact on the community structure.