Cyperus esculentus is an important species for agriculture developing in sandy area in China. The arid and saline habitat in the northern sandy region is a major obstacle for introduction of C. esculentus. This paper aims to reveal the effects of different irrigation and salinity conditions on the composition structure and functional group characteristics of soil fungal communities in C. esculentus field in Horqin sandy land. A random plot sampling experiment was conducted with two-factor, three-level (irrigation level:50%, 70% and 100% of standard irrigation quota; salt level:non-saline, weakly saline and medium saline soils) to study the characteristics of soil fungal populations of C. esculentus under different irrigation and salinity treatments, in C. esculentus field in Songyuan City, Jilin Province. Results showed that:(1) a total of 2354 fungal operational taxonomic units (OTUs) were obtained in soil sample collected in C. esculentus field, which belonged to 13 phyla, 3 classes, 43 orders, 224 families and 434 genera. Ascomycota ((67.83±6.33)%), Mortierellomycota ((16.96±6.02)%) and Basidiomycota ((11.31±1.82)%) were absolutely dominant in the fungal community. With increasing irrigation, the dominant fungal genera changed from Mortierella ((22.8±7.41)%) to Fusarium ((11.52±3.91)%) and Chaetomium ((11.35±4.64)%). There was no significant difference in fungal diversity among different irrigation and salinity treatments (P>0.05). (2) The fungal functional groups were dominant by saprophytic trophic types, followed by pathotrophic trophic types, and the symbiotic trophic type was the lowest one. Both symbiotic and saprophytic trophic fungi reached the lowest value in 70% standard irrigation quota conditions, when pathotrophic fungi reached utmost. Both saprophytic and pathotrophic fungi didn't show significantly different in different salinity stress levels. (3) There was no significant interaction between different irrigation and salinity treatments on the structure and function of soil fungal communities in C. esculentus field. (4) The main effect factors on soil fungal communities in the study area included soil moisture and total phosphorus content. The total phosphorus content in soil was negatively correlated with Chao1 index (P<0.05). Soil physicochemical properties were not significantly correlated with fungal trophic type (P>0.05). The irrigation amount in the study area affected the composition of dominant genera of fungal communities and altered the relative abundance of saprophytic and pathotrophic fungal groups. This study contributes to understanding the formation mechanisms of soil fungal communities in C. esculentus field, further revealing the effects of water-salt interaction on soil fungal community composition and fungal eco-functional group characteristics in C. esculentus field, and also provides a theoretical basis for better introduction and irrigation strategies of C. esculentus in saline lands.