Abstract: A loach was collected from Nanla River Basin in Mengla County, Yunnan Province, which flowing into Lancang River (Upper reach of Mekong River) in July,2001. By comparing with related species, this specimen is proved as a new species and described below. Schistura bannaensis sp. nov. (Fig. 1a) Holotype No: KIZ 200107, 42.5mm SL, 48.8mm TL, Nanla River Basin,Mengla County, Yunnan Province. This specimen is now deposited in the Museum of Kunming Institute of Zoology, Chinese Academy of Sciences. D.ⅲ-7; P.ⅰ-8; V.ⅰ-6;A.ⅲ-4 1/2;branched caudal-fin ray 15. Depth of body in standard length 7.1, length of head 5.8, length of peduncle 6.5,its depth 9.0. Length of snout in length of head 2.1, diameter of eye 5.2, width of interorbital space 3.5. Depth of peduncle in its length 1.4. This new species is similar with S. latifasciata (Zhu et Wang, 1985) and S.crabro Kottelat, 2000. But it differs from S. latifasciata in the combination of following characters: 1) Dorsal fin ⅲ-7 Vs ⅲ-8;2) 4 broad dark brown bars, upper part wider than interspace of bars and lower part narrower than or equal to interspace Vs 4-6 dark brown bars, narrower than interspace;3) no longitudinal black bar along the lateral line Vs a longitudinal black bar along the lateral line; 4) caudal fin forked and tips of the two leaves a little pointed Vs caudal fin concave, and the tip of the two leaves round; 5) the tip of the ventral-fin not reaching the anus Vs the tip of the ventral-fin reaching or near the anus. It also differs from the species S. crabro in the combination of following characters: 1) Dorsal fin ⅲ-7 Vs ⅲ-8; 2) lateral line complete Vs lateral line incomplete, reaching vertical of middle dorsal-fin base; 3) no black pigments forming a band from the first bar to caudal-fin base Vs a swarm of black pigments forming a very broad band from the first bar to caudal-fin base; 4) no black blotch in cheek Vs a black blotch on cheek; 5) the part of black bar upper the lateral line broader than that under the lateral line Vs some of the black bars with the equal breadths of the upper parts and lower parts; and the fourth black bar complete Vs the fourth black bar incomplete, and the upper part narrower than the lower part.