According to field investigation and relative data, the species composition, origin and life form were studied, the similarity of different species in different areas was compared, and the spread- ing tendency on part of high dangerous invasive alien plants was predicted. The study showed that 148 species of invasive alien plants belonging to 105 genera of 41 families were identified in three provinces of South China. There were 132 species of invasive alien plants in Guangdong, 129 species in Guangxi and 100 species in Hainan, in which the most were Asteraceae, Gramineae and Amaranthaceae. The most of the invasive alien plants were from America with 108 species, taking up 73.0% of the total species. The species of herbaceous invasive alien plants were the most with 114 species, taking up 77.0 %. The similarity of species composition of invasive alien plants between Guangdong and Guangxi was the highest, the lowest between Guangxi and Hainan.