[Objective] The effects of Salix psammophila sand barrier decay on the composition and diversity of fungal communities were analyzed in order to provide a theoretical basis for further research on the ecological function of fungal communities in desert ecosystems. [Methods] S. psammophila sand barriers aged 1, 3, 5,and 7 years were observed, and newly laid sand barriers were used as the control. Field in-situ sampling, laboratory index determination, and Illumina MiSeq sequencing technology were used to determine the response relationships between fungal diversity and sand barrier components, soil properties, and enzyme activities during sand barrier decay. [Results] ① The relative abundance of Phialophora, Trichoderma, Knufia, Veronaea and Coniochaeta increased over time, while Didymella and Phaeococcomyces decreased over time. Fungal diversity and richness increased over time. ② Soil organic carbon, alkaline nitrogen, and dissolved organic carbon at seven years were 2.47, 1.83, and 1.71 times higher, respectively, than observed for the control. Activities of β-1,4-glucosidase and leucine aminopeptidase significantly increased by 139.36% and 35.16%, respectively. ③ Knufia, Parasola, Veronaea, and Coniochaeta were positively correlated with soil organic carbon, alkaline nitrogen, and dissolved orgainic carbon, but negatively correlated with cellulose and hemifiber (p＜0.05). The results of the redundancy analysis showed that cellulose and alkaline nitrogen were the main environmental factors that significantly affected the abundance of dominant fungal communities, and alkaline nitrogen and leucine aminopeptidase were the main factors that influenced the diversity index. [Conclusion] Both the dominant fungal genera and diversity were affected by a combination of factors during S. psammophila sand barrier decay. Alkaline nitrogen was the main influencing factor for both dominant fungal genera and diversity. Future studies should further explore the ecological functions of the dominant fungal groups in combination with the FUNGuild database.