Based on the similarity criteria of incipient velocity, an experimental study is performed on a 1∶60 overall physical model to study the sediment flushing effects and sand funnel patterns of two desilting galleries and one bottom tunnel under designed operating conditions to provide a basis for the design and arrangement of the desilting facilities in front of the Dagu Hydropower Station Dam. The results show that the ultimate desilting effect is less affected by the operating order of the desilting tunnels. The patterns of sand funnels are mainly determined by the sediment property, and the slope of the sand funnels is close to the underwater repose angle of non-cohesive sediments under deep reservoir water level. The design scheme for the desilting facilities in Dagu Hydropower Station guarantees the condition of clear in front of the hydropower intake.