The diversity of arbuscular mycorrhizal fungi (AMF) is a crucial indicator for determining the productivity of forest ecosystems and for assessing degraded areas. At present, the effect of tree age and vegetation restoration strategies on AMF diversity in karstic rocky desertification areas remains unclear. This study investigated AMF diversity and abundance in soils planted with Delavaya toxocarpa Franch. for 18, 11, and 4 years in a karstic desertification area of southwestern China. Additionally, it explored AMF community composition in soils of an 18-year-old D. toxocarpa plantation, a secondary forest naturally restored since 2005, and an abandoned land with no human intervention. High-throughput sequencing revealed that the mean Chao1 and richness indices of AMF increased with tree age, as indicated by the highest AMF alpha-diversity in 18-year-old plantations. The various vegetation restoration strategies resulted in significant differences in AMF abundance and evenness indices. Although no significant differences (p = 0.33) were found between the different restoration strategies, the AMF alpha-diversity index showed a decreasing trend from plantation forest to secondary forest and then to abandoned land. Overall, soil organic carbon (SOC), total nitrogen (TN), and available phosphorus (AP) significantly influence AMF diversity. Additionally, soil TN, AP, hydrolysable nitrogen (HN), and urease activity (URE) shape AMF community composition. These properties varied with tree age and vegetation restoration strategies. Our findings point to good recovery results of artificial afforestation in karstic rocky desertification areas. The process accelerates vegetation restoration and enhances the mutually beneficial relationship between vegetation and AMF compared with natural restoration. However, the tree age selected in this study only represents the forest stands before mature forests, and the microbial diversity and structure in karst rocky desertification soils after mature and over-mature forest stands remain to be studied.