Abstract: Mycorrhizal seedlings are the basis of mycorrhizal synthesis of Tuber melanosporum on the trees roots in the soil. Four species of seedlings were inoculated by using 1-4 mL liquid inoculum of T.melanosporum. After 90 days, the percentages of mycorrhizal infection were 94.4%100%. The mycorrhizas had four forms, in which the coral form was the most common, followed by the stick and bifurcate forms, while the spherical form was the least. But the proportion of each mycorrhizal form was different on various tree species. After inoculation, the height of seedlings of Pinus yunnanensis with T. melanosporum was increased by 76.67%-131.74%, the mean dry weight was increased by 162%-217%. The seedlings with 4 mL liquid inoculum performed better. The results of media experiment with different pH values showed that the pH 6.5-7.0 had higher inoculation rate and biomass increment as well as better seedling growth.