Abstract: The Gelongbu landslide located at the reservoir region of Jishixia hydropower station dam in upper reach Yellow River. Its volume was of 50.4106 m3. It had 4 regions. The result of landslide investigation indicates that the formation mechanism of Gelongbu landslide is sliding-fracturing. The landslide debris flew down with a high speed on the right side of Yellow River and hit a hill. . Part of its debris flew across the river and deposited on the left side. Its debris had blocked the river for several hundred years and formed a landslide dam like. The thickness of sediment in the landslide dam lake was 30 m based on the measurement of this investigation. Height of the landslide dam was about 100 m and water depth of the lake was about 70 m based on the preliminary analysis of this investigation. The epoch of landslide is Q4. The debris were still left on left and right sides of Yellow River. The Yellow river path was changed at this location. It was possibly due to a sudden collapse of the landslide dam. 