Five bat individuals were collected by mist net from Maogan Town,Baoting Li and Miao Automomous County,Hainan Province in November 2007.Morphological measurements and analysis on mitochondrial ND1 gene suggested that it was Ia io(Vespertilionidae;Chiroptera).This was the first record of this species in Hainan Province.In the present study,morphological characters and echolocation call parameters were represented detailedly.Comparisons were also performed between our findings and published data about the species recorded in other areas.