Abstract: Based on an investigation of bryophytes on ten islands and one peninsula of the southeastern sub-region of the Thousand-Island Lake,the composition of bryophytes and the effects of habitat fragmentation on their diversity were studied.The results showed 129 species belonging to 71 genera and 37 families,among which 3 species were new to Zhejiang province.Geophytia,petrophytia and epixylophytia were dominant bryophyte communities.The bryoflora of the Thousand-Island Lake was characterized by East Asia elements represented by 39.45% of the entire species,followed by North Temperate elements and Tropical Asia elements which accounted for 20.18% and 18.35%,respectively.The distribution of 58 bryophyte species was affected by island area,while 29 species was unaffected.The relationship between island size and bryophyte richness showed a positive correlation.