During the survey on bats for specimen collection in June,2010 at Sandu County,Guizhou Province,one specimen of Vespertilionidae,collected at Shuilong Township,was identified as Least Pipistrelle (Pipistrellus tenuis).Description as follows: small body size,the forearm length 30.64 mm; the greatest length of skull 12.04 mm.Ears large,with broadly rounded tip; tragus length is half of pinna.The upper canine usually bicuspid,and the first upper premolar sufficient contact with canine base and slightly inside toothrow.Lower canines well-developed,and exist a small tip in lateral.Baculum length 3.82 mm.