In order to study the reproductive biology of Gymnocypris waddellii Regan, we collected 225 fishes in Karuxung River and Rongbuk Zangbo River which are located in Yanmdrok region from March to July in 2006.The results show that G.waddellii Regan has anadromous habit and reproduces from May to August with water temperature of 9.5-18.5℃, flow rate of 0.3-0.8m/s and depth of 15-50cm.All female and male firstly start to reproduce at 5 ages and their secondary sexual features are significantly different between male and female.The smallest sex mature male with 80 g weight has mature coefficient of 4.6% with body length of 19.5cm.The smallest sex mature female with 95 g weight has mature coefficient 6.3% with body length of 21cm.Tile mature eggs are orange and round balls with diameter ranging from 1.92 to 3.32mm, and the mean diameter of mature eggs is 2.22mm.The number of eggs within one gram varies from 63 to 214 eggs with mean of 115 eggs.The absolute fecundity of brood stocks varies from 1086 to 11400 eggs and the mean is 4446 eggs.The relative fecundity varies from 6.2 to 36.1 eggs/g with mean of 18.0 eggs/g.The mature coefficient varies from 5.7% to 25.8% with mean of 16.2%.The brood stocks are composed mainly of individuals aged 8, 9 and 10 with sex ratio of females to males of 1:1.16.Fecundity was positively correlated with body length and weight, respectively.