Although plenty of ectomycorrhizae are associated with pines, actually few ectomycorrhizae are developed into application. To obtain the ectomycorrhizal fungi having great abilities of mycorrhizal formation with pine seedlings, in this paper mycorrhizal formation of 7 strains of ectomycorrhizal fungi with seedlings of Pinus elliottii, P. massoniana, and P. thunbergii were tested with two inoculating methods: seeding and transplanting seedlings with root apices cut off, The results showed that the dominant form of ectomycorrhizae was dichotomous branching and unbranched ectomycorrhizae were less. Multiple branches of the ectomycorrhizae were more frequently developed on P. massoniana. Surface hyphae of mycorrhizae developed by Pt2 were thick and dense, followed by Boletus edulis (504), Amanita pantherina (EG) and Pisolithus tinctorius (Pt1) and surface hyphae developed by the other fungal strains were sparse. Extraradical hyphae of mycorrhizae developed by P. tinctorius (Pt1, Pt2) and A. pantherina (EG) were longer, while extraradical hyphae of mycorrhizae developed by Boletus speciosus (505) and Rhizipogen luteous (HX) were very short. The method of cutting off root apexes of the young pine seedlings and then inoculating ectomycorrhizal fungi showed higher infection rate and index than inoculating during seeding. The ability of Boletus edulis (504) was the greatest in developing mycorrhizae among all the tested ectomycorrhizal fungi and its infection rates with the seedlings of three pine species were all 100%, its highest infection index reached 90 and the lowest infection index was 70. The abilities of Pt2 and EG were greater in developing mycorrhizae with P. massoniana and P. thunbergii, but 505 and HX only had greater abilities in developing mycorrhizae with P. massoniana. The ability of Pt1 was the worst, because it had low infection rates and indexes with the seedlings of three pine species. Among the seedlings of three pine species, P. massoniana was the best in mycorrhization, followed by P. thunbergii and P. elliottii in a descending order.