Understanding the effects of land-use changes on arbuscular mycorrhizal fungal (AMF) communities may greatly benefit ecosystem conservation and restoration. However, how AMF communities respond to anthropogenetic land-use change (e.g., from natural ecosystems to farmland ecosystems) is still under debate. To enhance the preservation of vegetation diversity in ancient tea forest (ATF) regions and understand how land-use changes influence the AMF community in acidic soils, the AMF community composition and assembly processes in the ATF region (soil pH: 3.5–4.2) were investigated. Our results showed that AMF α-diversity indices in ATF were significantly higher than those in conventional tea plantations (CTP) and Forest. Moreover, number of indicator species (as virtual taxa, VTX) showed a remarkable decrease when ATF (12 VTXs) changed to Forest (8 VTXs) and CTP (3 VTXs). In addition, neutral processes dominated the AMF community assembly, and Acaulospora was the dominant genus of AMF indicator species in ATF. Moreover, land-use changes eliminated the neutral process of AMF community assembly in CTP and Forest by enhancing the environmental filtering effects. The concentrations of soil nitrate, TK, Mg²⁺, and Cu²⁺ were important factors accounting for the AMF community change. In addition, we found that high acidity soils may exert an ecological selection on the AMF community, as only species that adapt to strongly acidic soils persisted. Overall, our results indicated that mitigating soil acidification has potential as a method of improving the AMF community diversity and conserving and restoring ATF ecosystems in southwest China.