Abstract: The mycota on healthy barks from three species of poplar with different resistant to poplar canker were isolated from March to November,1996 and 123 species belonging to 67 genera were identified.The most common genera on three poplars barks were Aspergillus, Alternaria, Drechslera, Penicillium, Chaetomium, Trichoderma, Coniothyrium, Rhizopus and Mucor.The mycota of three poplars were different in terms of percentage of dominant species.Species composition increased from upper stem to downwards.The diversity and quantity of fungal species on branches increased with the age of the branches; more species and high population were found on the outer bark; the tendency of seasonal dynamic variation of fungal quantity was higher in summer and autumn, lower in spring and winter.Alternaria, Aspergillus, Drechslera and Chaetomium were the dominant genera on Populus tomentosa; Alternaria, Aspergillus, Trichoderma and Penicillium were the dominant genera on Populus deltoides cv.’Lux’×P.cathayana 1062; Alternaria, Aspergillus, Coniothyrium and Penicillium were the dominant genera on Populus×beijingensis.