To reveal the fungal community structure and functional groups in the roots associated with P. sylvestris, natural forest and different-aged plantations were analyzed using field investigation and molecular biotechnology in the Hulunbuir Sandy Land. 520 fungal OTUs were obtained from root tip samples of P. sylvestris, and belonged to 197 genera, 87 families, 5 phyla. Basidiomycota and Ascomycota had higher relative abundances, accounted for 54.98% and 39.27% respectively. The dominant bacteria in natural forest were Geminibasidium, Russula and Phialocephala, whereas the dominant bacteria in plantation were Suillus, Phialocephala and Tricholoma. Further, the relative abundance of other bacteria fluctuated with the stand age. The α diversity index of fungi in the roots of P. sylvestris plantation decreased gradually with the increasing of stand age. Among the different stands, the fungal diversity in the roots of mature forest was significantly lower than that in near-mature and middle-aged plantations as well as natural forest (P<0.05). Although the fungal community composition associated with P. sylvestris natural forest and plantations had stable variability, and near-mature forest is the closest to natural forest, natural forest and mature plantation obviously differed in the composition of fungal community. The proportion of symbiotic trophic fungi increased with the increasing of stand age. Conversely, the saprophytic and pathological trophic fungi decreased with the aging forest. The proportion of symbiotic trophic fungi in natural forest was similar with near-mature plantation, however saprophytic trophic fungi was the dominant type in natural forest. In the Hulunbuir Sandy Land, the fungal community in the root of P. sylvestris has complex structure and diverse species. The main functional groups are ectomycorrhizal and undefined saprophytic fungi. Some fungi show different ecological strategies in different stands.