Abstract: In order to clarify the diversity of ectomycorrhizal fungi of Betula albo-sinensis and Larix gmelinii in the Taizishan forest area of Gansu Province, molecular biological methods were used to study the ectomycorrhizal fungi diversity of Betula albo-sinensis and Larix gmelinii. The ressults showed that the top five ectomycorrhizal fungi of Betula albo-sinensis were penicillium, penicillium paecilomyces, mucor, plectomyces and chaetchium in the Taizishan forest area of Gansu Province. The top five ectomycorrhizal fungi of Betula albo-sinensis in the Taizishan forest area of Gansu Province were penicillium, spodophyllum, trichocladosporium, trichocladosporium and trichocladosporium dactyloides. The young Betula albo-sinensis and Larix gmelinii species in the Taizishan forest area of Gansu Province and the sunny slope are more susceptible to ectomycorrhizal infection and have higher fungal diversity. The diversity of ectomycorrhizal fungi of red Birch was higher than that of Larch. Tree age and slope orientation had significant effects on ectomycorrhizal fungi diversity of Betula albo-sinensis and Larix gmelinii. The results can provide theoretical guidance for afforestation in the Taizishan forest area of Gansu Province.