【Background】Guangdong Province is one of the most seriously affected areas by invasive species. Many alien aquatic species have been found in the rivers of Guangdong Province, but we lack a detailed description of their distribution and abundance. 【Method】In the present study, filed survery was conducted to assess the distribution of alien aquatic species in the main rivers of the Guangdong Province including the Pearl River (Xijiang River, Beijiang River, Dongjiang River), Hanjiang River, Jianjiang River and Tanjiang River, and the invasion mechanisms of these invasion species were investigated preliminarily. 【Result】Thirteen alien aquatic species were found, including 11 vertebrates such as Trachemys scripta elegans, Oreochromis niloticus, Oreochromis mossambica, Oreochromis aureus, Hypostomus plecostomus, Clarias leather, Cambusia affinis, Cirrhina mrigala, Labeo rohita, Lctalurus punctatus, Micropterus salmoidesand 2 invertebrates such as Pomacea canaliculata, Procambarus clarkia. T.scripta elegans, Pomacea canaliculata and three tilapias were most widespread. 【Conclusion and significance】The invasion of these alien species resulted from introduction by people for aquaculture, escapes or discarded from recreational fisheries or were introduced as biological control agents. Omnivorous fish more easily became successful invaders than others.