There was a catestrophic flood in Yeerqiang river of Xinjiang in Aug.30,1984, which lost about 500000 yuan on damage water conservancy projects along the river and cost 300000 yuan for rush repairing. Since 1949, there had been carried out in th source of the river by a united team of department of water conservancy of Xinjiang and Institute of Glaciology and Geocryology, Academia Sinica etc. It was found that the flood, coming from the modern glacier area of the source, was caused by breaking of ice-dam and coffer-dam lakes formed by blocking of river with glacier movement.