Abstract: We studied the anatomical structure changes of the different ectomycorrhizal roots of Pinus thunbergii seedlings inoculated with Rhizopogen luteous (Rl), Pisolithus tinctorius (Pt), and Boletus edulis (Be). The results indicated that the anatomical structures of the ectomycorrhizas showed significantly difference in stele, cortex, mantle structure and Hartig net distribution after 14 months of inoculation compared to noninoculated seedlings (the control). The ectomycorrhizas inoculated with Rl and Pt had smaller stele and larger cortex in root cross section, and highlybranched Hartig net hyphae were distributed among cortical cells. The thickness of mantle was not obviously correlated with the seedling growth in all treatments, but pseudoparenchymatous in the mantles inoculated with Rl and Pt were developed, and well integrated with the roots. Our study helped to understand the mechanism of plant growth promoting by mycorrhizal fungi.