Abstract: The double row perforated cylinder breakwater is a new composite structure based on the cylinder and plate breakwater. The three-dimensional numerical wave flume is established based on the incompressible two-phase flow model. The turbulent closure is carried out by RNG k-ε turbulence model, and the TruVOF method is used to capture the free liquid surface. The influence of relative row spacing and opening rate on the wave dissipation performance of double row perforated cylinder breakwater is explored, and the special hydrodynamic phenomena and flow characteristics near the back row perforated cylinder breakwater are analyzed. The results show that in the range of working conditions studied in this paper, the along-range average wave height increases and then decreases with the increase of relative row spacing, and increases with the increase of opening rate, and the effect of period on the along-range average wave height has no obvious rule; when B/D = 9, e = 23.11%, the double row perforated cylinder breakwater has the best wave dissipation effect, the reflection coefficient ranges from 0.4 to 0.46,the transmission coefficient is between 0.3 ~ 0.35, the dissipation coefficient is between 0.8 ~ 0.85. Free surface fragmentation, water-air mixing and annular eddy motion evolution are the main causes of wave dissipation and energy dissipation of double-row cylinder breakwater. The jet stage occurred more violent free liquid surface fragmentation and water-gas mixing, resulting in the increase of turbulent kinetic energy after the dike, the peak turbulent kinetic energy after the increase is about 2.5 times of that before the jet, and the violent turbulent energy dissipation occurred. The relative row spacing will cause the changes of vorticity distribution and shear layer morphology near the rear breakwater, which will lead to different turbulent characteristics and affect the wave breaking characteristics of the double row perforated cylinder breakwater. The research results can provide theoretical support for the engineering design of a new type of double-arranged cylindrical breakwater and the study of wave dissipation mechanism.