Abstract: For 6-8 months each year from 1983 to 1988, we made investigations on the fauna of Tabanidae and its vertical distribution on the southern slope of Taibai Mts. A total of 46 species in 5 genera were obtained, which included 7 species of Chrysops belonging to the subfamilyChrysopinae, 3 species of Atylotus, 6 species of Hybornitra, 5 species of Haernatopota and 25 species of Tabanus in the subfamily Tabaninae. According to the the vegetation, climate and elevation above sea level, the southern slopeof Taibai Mrs was divided into 8 vertical zones. Among these zones, the number of species of the tabanids was highest in the Pinus-Qurcus forest (1000-1500 m), ie. 42 species accounting to 91.3% of the total species discovered, the second came the evergreen broad-leaf and deciduous forest (600-1000 m), in which 36 species were found according to 78.3% of the total, and the third was in the mixed forest (1500-2000 m) where 24 species according to 52.2% were found.In places below 600 m or above 2000 m less species had been discovered. The fauna of Tabanidae investigated could be considered as a transitional zone for Palaeartic to Oriental, the Palaeartic fauna is prominent, the zone in 600-2000m to be the tran sitional center, while that of 1000-1500m to be the division line between the two regions in Qinling Mountains.

Key words: Tabanidae——fauna——vertical distribution——Taibai Mts.