Abstract: In order to study the mycorrhizal effects of mycorrhizal seedling after transplanting, three nitrogen (N) levels, 45, 67.5 and 90 kg/ha, were applied in field experiments and the effects of mycorrhizal seedlings on phosphorus (P) content in soil and N and P absorption of plants at fast growing stage were studied. The results showed that:1) The effects of Arbuscular mycorrhizal (AM) fungus inoculating on the P content in tobacco planting soil and tobacco plants were insignificant at the N application level of 45 and 67.5 kg/ha, however, P content would be effectively improved at the level of 90 kg/ha. 2) The N contents in tobacco root, stem and leaves were remarkably decreased by Glamus mosseae(Gm01)inoculating at different N application levels, but, Glamus mosseae(Gm02)inoculating was remarkable only at the application level of 90 kg/ha. 3) The N/P ratio in tobacco was effectively decreased by AM fungus inoculating at different N levels, however, Glamus mosseae (Gm01)inoculation was more effective. It indicated that N application would affect the mycorrhizal effects of AM fungi, but the effects of Glamus mosseae from different origin differed to a certain extent.