Abstract: With snow line (as snow falls in winter or melts in spring, place rat clamps up and down along border of snow line of the mountain to capture rodents and collect flea specimens outside their bodies) and routine investigation methods, selecting 7 different representative altitude gradients and 6 different habitat types, an 11 years' continuous study had been carried on in the eastern part of Daba Mountains in Hubei. The results showed that：1) of the 51 species of 9 974 fleas collected belonging to 28 genera of 8 families, 25 species belong to the Palaearctic region (49.02%), 21 belong to the Oriental region (41.18%) and 5 are wide_spread (9.80%)；evaluated with individual proportion, the difference between the Palaearctic region (37.97%) and the Oriental region (50.30%) is not as obvious as species composition；2) the faunal characteristics of vertical distribution of fleas in the eastern part of Dabashan Mountain is that the Oriental species occupy absolute predominance under altitude 1 500 m；the Palaearctic species account for 44.82%-56.41% at altitude 1 600-2 300 m, while the individual proportion of the Palaearctic species is 33.47%-60.16% at the same altitude range；some special indicators in the Oriental region such as Typhlomyopsyllus bashanensis and its host Typhlomys cinereus can be seen in the Palaearctic region；when the altitude is elevated to 2 600 m, the Palaearctic species account for 55.00%, and T. bashanensis and its host T. cinereus can not be found any more；when the altitude was above 2 800-2 980 m, the Palaearctic species proportion and individual proportion are 65.00% and 89.51%, respectively；3) of the 51 species of fleas in the eastern part of Daba Mountains, 24 species are also distributed in Qinling Mountains, accounting for 70.58% of 34 species known in Qinling； the Palaearctic species proportion in the two mountains was 49.02% and 52.94% respectively. According to principles of similarity in faunal elements, host animals,  vegetation zone and geographical conditions, the altitude lineation (1 000-2 000 m) of fleas in the south slope of Qinling Mountains proposed by Zhang Jin-Tong et al. (1989) was revised and elevated to about 2 600 m. The position and direction of the revised altitude lineation is corresponding to lower border limit of subalpine coniferous forest. Above the line, the Palaearctic elements dominate in both species number and individual number; while below the line, there exists a mixture of the Oriental, the Palaearctic and some endemic elements. In the author's opinion, although the fauna of animal species is a key indicator in determining the characteristics of mountain fauna, the faunal proportion of species and individuals and the living extent of some animals with special indications are of greater significance in altitude lineation to comprehensively determine the property of animal fauna. Meanwhile, it can make people better understand the vertical distribution of the Palaearctic and the Oriental elements in mountains and make wiser judgment conforming to the reality.

Key words: Fleas, faunal composition, vertical distribution, Palaearctic region, Oriental region, altitude lineation, eastern part of Daba Mountains