Abstract: Mimosa pigra L., a noxious shrub, has invaded in tropical region of the world, is reported as a new record of naturalized invasive plant of Mainland of China. The population of M. pigra has been discovered in the riverbank of Nandu River of Haikou City, Hainan province, China. In this paper, the distribution information in Mainland of China was given, and some discussion about the weed was made.