【Objective】Arbuscularmycorrhizal (AM) fungi are ubiquitous in the terrestrial ecosystem and capable of forming mutualistic relationships with most high plants, increase soil carbon sequestration via both direct and indirect pathways, and then play a key role in building up carbon storage in the forest ecosystem. However, little has been reported in the literature about variation of the AM fungus community in the soilunder long-term plantation of moso bamboo (Phyllostachysedulis). Hence, the primary concern of this study is to explore variation of soil AM fungus in biomass and community structure, and its key affecting factors in the soil under long-term planted moso bamboo forest.【Method】As the moso bamboo forests in this area were mostly converted from masson pine forests one by one in the past years, plots of moso bamboo stands different in plantation age (i.e. 5 a, 9 a, 15 a and 18 a,)for comparison with the plots of natural masson pine forest. Each plot (10 × 10 m) had three replicates and all the plots were laid out at least 10 m apart.Five sampling points were set randomly in each plot, and samples of topsoil (0~20 cm)were collected from the five sampling sites in each plot and thoroughly mixed up to make a single composite sample for each plot.The soil samples were analyzed forbiomass and community structure of AM fungi using the phospholipid fatty acid (PLFA) method and the high-throughput sequencing based on the IlluminaMiseqplatform method, respectively.Glomalin-related soil protein (GRSP) was extracted with citrate solution and measured by spectrophotometer using boving serum albumin as standard. Soil water-stable aggregates were analyzed using the wet-sieving method.【Result】Results show that soil nutrients decreased in content with the moso bamboo plantation increasing in age. Moreover, the 18 year old plots were significantly lower than the 5 plots in both GRSP content and AM fungal biomass. Pearson correlation indicated that the content of easily extracted GRSP in the soil was positively related to organic C, available K, and available N (p<0.05), and AM fungal hyphal biomass (16:1ω5 PLFA) positivelyand significantly to available N (p<0.01). Fractionation of soil aggregates reveals that water-stable macroaggregates (2~0.25 mm in diameter) comprised the largest fraction of soil aggregates, varying in the range from 57.79% to 72.40% and long-term bamboo plantation reduced the fraction significantly. The percentage of macroaggregates was found positively and significantly related to the biomass of AM fungal hypha (p<0.01). Results of high-throughput sequencing indicate that Glomus dominated in the AM fungal community, followed by Acaulospora. In soils under long-term moso bamboo plantation soil Glomus increased in relative abundance while Acaulospora decreased significantly (p<0.05). Non-metric multidimensional scaling (NMDS) analysis demonstrates that the AM fungal communities in the soils under moso bamboo plantation varied sharply from those under masson pine plantation (p=0.001) and also significantly with age as was observed on the first axis of NMDS. When environmental variables were fitted onto NMDS ordination, AM fungal communities were found significantly related to soil moisture (p=0.005) and available N(p=0.001), but marginally to available P(p=0.014). 【Conclusion】Long-term plantation of moso bamboodecreasesAMfungalbiomass,alters AM fungal community structure significantly and exhausts soil nutrientssteadily. The changes in soil moisture，available P and available N contribute significantly to the variation of soil AM fungal communities. Long-term plantation of moso bamboo also decreasesthe content of GRSP,and theproportion of soil water-stable macroaggregates (2~0.25 mm) significantly, which poses a negative impact on soil carbon sequestration and hence stability of the ecosystem.