Abstract: Based on agar plate tests, 18 isolates from 23 white rot fungi were selected to a subsequent wood block decay test. According to the ratio of Klasson lignin losses to holocellulose losses, three isolates, Perenniporia ochroleuca D9597, Funalia trogii C6978 and Trametes orientalis C6320, showed selective delignification on Populus nigra. Based on primary component analysis, three different types of degradation were found during the fermentation of P. nigra by 18 white rot fungi: type A represents selective delignification; types B and C can selectively decompose holocelluloses, but type C has a stronger capacity than type B. Investigation was carried out on the UV absorbance spectra of ethanol extracts of wood particles treated by P. ochroleuca D9597, F. trogii C6978 and T. orientalis C6320 for 20 days, and lignin in the treated wood was found to be decomposed markedly.