Abstract: Based on investigation and reference consultation,plant species diversity and vegetation of Ung Kong Islands in Hong Kong were studied,including flora composition,characteristics,distribution type,and its relationship with neighboring regions.Results showed that there were 166 vascular plants belonging to 138 genera and 69 families,including 10 species in 8 genera and 7 families of ferns,2 species in 2 genera and 2 families of gymnosperms,and 154 species in 128 genera and 60 families of angiosperms in the Ung Kong Islands.The dominant vegetation types were shrub land and shrub-grass land,while cliff vegetation and evergreen broad-leaved forest were secondary.Each island had its own characteristics in regards to vascular plant biodiversity,as a result of different areas,altitudes and isolation levels.The flora of the Ung Kong Islands show high similarity with Ninepin Group,but much more difference with that of the Po Toi Islands.