Two specimen of Vespertilionidae were collected from Jiajiu Township in Congjiang County, Guizhou Province, during a survey of bat species diversity in August, 2010, which is identified as Nyctalus aviator and new record to Guizhou. Description as follows: Size large, thumb short with strong claw; calcar keeled; fur dense and velvety; color deep yellowish brown; upper inner incisor longer than outer incisor; the forearm length is 59.72-60.22 mm; tragus short and stubby; antitragus long and low; fifth finger shortest, third longest; wing membrane attached to ankle; tip of tail barely extends past uropatagium; skull broad and robust; lambdoidal crest conspicuous; postorbital process weak; teeth large, with low cusps, the upper toothrow length is 9.12-9.28 mm; first upper premolar was small and pushed to inner side of toothrow; second upper premolar developed;The lower toothrow length is 7.70-8.14 mm. The distribution range of this species extended to southwestern China, which differs from the record before. The specimens were preserved in the School of Life Sciences, Guizhou Normal University, Guiyang, China.