Abstract: On July 25-26, 2017, a rainstorm fell in the Wudinghe River watershed, where the largest flood occurred since monitoring in the Dalihe River, a tributary of the Wudinghe River. A hyperconcentrated flood was generated downstream of the Wudinghe River. To understand the sediment yield and transport in the Wudinghe River watershed during the rainstorm, a typical small catchment was selected to survey soil erosion and monitor sediment retaining of the check dam, as well as urban area siltation and channel scouring, with analysis of sediment yield at slopes and gullies by various approaches. Rainstorm concentrated locally with 24 hours maximum precipitation reached 100-year frequency. Baiwenchuan Hydraulic Station recorded the second maximum flood discharge since its establishment, with an extremum 873 kg/m³ sediment concentration. 64.1% of sediment came from the Dalihe River watershed during the flood. Taking Mehulu check dam as an example, the sediment yield of the Wudinghe River watershed was about 0.124 9 billion ton with 70% ~85% from gully slopes. Check dams played a key role in reduction of sediment transport into the Yellow River.