Abstract: A loach Triplophysa (Triplophysa) nujiangensa sp.nov.(Holotype:KIZ 20007496,61.1 mm SL) has been recognized on basis of two series of collections from main stem of Nu Jiang (Salween) in Nujiang Prefecture,July 2000 and Baoshan City,Yunnan,China,July 2004.Triplophysa (T.) nujiangensa is closely related to T.(T.) tanggulaensis (Zhu),T.(T.) stoliczkae (Steindachner),T.(T.) crassilabris Ding and T.(T.) stenura (Herzenstein).It can be distinguished from T.(T.) stenura,which also occurs in upper Nu Jiang,by following characters:caudalpeduncle depth not decrease prominently vs decrease prominently;caudal-peduncle width is smaller than its depth vs larger than;caudal-peduncle length 1.6-2.8 times its depth vs 4.7-9.5 times;papillae-like process on edge of upper lip absent vs present and form a prefringe;papillae on lower lip absent vs present.It can be distinguished from T.(T.) crassilabris by following characters:branched dorsal fin ray 8 vs 7;branched pectoral fin ray 10-11 vs 8-9;gill rakers 10-19 vs 8-9;intestine loops 3 vs 4-5;lower lip interrupted vs continuous;interorbital space convex vs flat;interorbital width 0.6-0.8 times caudal-peduncle length vs almost equal to;predorsal length 71.1%-77.2% standard length vs about 50%;pelvic fin not reach anus vs reach or surpass;caudal fin emarginate vs truncate.Its spade-like lower jaw with sharp and straight edge is closer to T.(T.) stoliczkae,while its snout bending down anterior to nostril is closer to T.(T.) tanggulaensis;its gill rakers 10-19,just between T.(T.) stoliczkae and T.(T.) tanggulaensis.It can be distinguished from both T.(T.) stoliczkae and T.(T.) tanggulaensis by the following characters:predorsal length 71.1%-77.2% standard length vs 47%-55% and 52%-57%;pelvic fin not reach anus vs reach.It can be further distinguished from T.(T.) tanggulaensis by its snout round vs pointed,cheek normal vs inflated,standard length 4.6-5.5 times head length vs 4.1-4.5,pectoral fin length 47.5%-63.5% distance between pectoral and pelvic fin origins vs about 75%.It has relative smaller body size than T.(T.) stoliczkae,standard length 45.6-73.1 mm vs 35.5-111 mm;and it can be further distinguished from T.(T.) stoliczkae by its body short vs slender,head more cylindral vs more triangular,snout bends down anterior to nostril vs head back straight,papillae-like process on edge of upper lip absent vs present and form a prefringe,papillae on lower lip absent vs present,paired fins rounded and short vs sharp and elongate.A key to Chinese Triplophysa with a spade-like lower jaw is listed in the text.