Abstract: Different mycorrhizal types in plants exhibit distinct strategies for resource acquisition and environmental adaptation. Elevation integrates multiple environmental factors and influences community structure and species diversity in mountain ecosystems. However, how tree species with different mycorrhizal types vary in diversity-elevation patterns remains poorly understood. A 3210 m continuous elevational transect (636–1928 m a.s.l.) was established in Baishanzu National Park, China, and we surveyed adult trees and saplings of three mycorrhizal types: arbuscular mycorrhizal (AM), ectomycorrhizal (EcM), and ericoid mycorrhizal (ErM). We calculated Hill indices (q = 0, 1, 2) to compare diversity-elevation patterns among mycorrhizal types and life stages. Bray-Curtis and Sørensen indices were used to quantify elevational changes in species composition dissimilarity between adults and saplings. Results showed that AM trees consistently exhibited higher species diversity than EcM and ErM trees. Elevation was the primary driver of diversity across all mycorrhizal types. AM diversity showed a hump-shaped relationship with elevation, whereas EcM and ErM declined monotonically with increasing elevation. Across all mycorrhizal types, adults showed a consistent hump-shaped elevation pattern, while saplings shifted from hump-shaped to monotonically decreasing patterns as q increased with abundant species weighted. Species composition dissimilarity between adults and saplings increased with elevation for AM trees, declined for EcM trees, and showed an inverse hump-shaped pattern for ErM trees. Overall, our findings reveal elevational diversity trajectories and regeneration dynamics among mycorrhizal types, highlighting the crucial role of mycorrhizal associations in shaping diversity-elevation relationships by mediating species abundance and regeneration across life stages in mountainous forests.