Abstract: In this study， fungal diversity of 12 deep-sea sediment samples from 4 sampling sites at Yap Trench were investigated based on culture-dependent method. A total of 38 fungal strains were isolated and the taxonomic identification was performed based on morphological observation and ITS sequence analysis. The results showed that all strains were affiliated with 10 genera， including Penicillium（17 strains）， Aspergillus（7 strains），Talaromyces（1 stain），Cladosporium（6 strains），Ochroconis（1 strain），Meyerozyma（1 strain）， Meira（1 strain），Cystobasidium（2 strains），Wallemia（1 strain） and Rhodotorula（1 strain）. The dominant genera were Penicillium， Aspergillusand Cladosporium， whose members accounted for 44.7%， 18.4% and 15.8% of all strains isolated. Furthermore， the nirK gene was detected in 18 strains belonging to 6 fungal species including Aspergillus flavus，Aspergillus niger，Aspergillus versicolor，Cladosporiumsp.，Cladosporium cladosporioides and Penicillium chrysogenumwhile the P450nor gene was only detected in Penicillium chrysogenum. Meanwhile， 2 denitrifying fungal strains were isolated based on enrichment method， both belonging to the genus Cladosporium. Results of this research indicated that there were abundant fungal resources in deep-sea environments and they might play an important role in the deep-sea nitrogen cycle， which should enhance the understanding of fungal diversity and their ecological roles in deep-sea environments.