The revised smooth particle hydrodynamics method based on the Riemann solution has been used to simulate the interaction process between waves and perforated caissons. In contrast to wave surfaces and opening boundaries of the flume under different wave conditions, the accuracy of the numerical wave flume is verified, and the numerical results are highly consistent with the linear regular wave theory. The reflection coefficient comparison between the values calculated from the smooth particle hydrodynamics method and the test data shows good agreement. The smooth particle hydrodynamics method adopted in this article can be employed to study the reflection coefficient of perforated caissons under conditions of non-overtopping, unbreaking waves. The effects of the related factors on the reflection coefficient are also investigated, including the relative dissipation chamber width B/L and the wave steepness H/L. The wave surface and velocity vector distribution of water particles surrounding the wave dissipation chamber are discussed, including the vortex flow and wave reflux caused by the wave dissipation chamber, which play a significant role in wave energy consumption. The results of this investigation can be used in the hydrodynamic design of perforated caissons and may provide a reference for offshore structural engineering structures.