Abstract: Based on the ecological characteristics and symbiotical relationship of ectomycorrhizae of Populus tomentosa,the research on the beneficial ectomycorrhizal fungi has been conducted.The results show that Scleroderma sp.is not only able to endure the high temperature as compared with the other fungi,but also to grow in the alkaline substratum.In neutral substratum all of the Tricholoma columbetta,Laccaria laccata and Scleroderma sp.could form ectomycorrhizae with the host plant and improve the host's growth,but in alkaline soil only Scleroderma sp.formed ectomycorrhizae,which bettered the host growth and its nutrient situations of nitrogen and phosphate.Its effect of inoculation rose obviously with the increase of the inoculum amount.A worse effect resulted from the inoculation experiment of Cenococcum geophilum.