In order to compare the difference of hydrodynamic characteristics between the caisson-type and comb-type breakwater，a numerical model of wave and the above two structures interaction is established based on OpenFOAM to analyze the reflection coefficients，wave pressure，and flow field distribution characteristics in different periods. The results show that：1）The reflection coefficient of the caisson-type breakwater is larger than the comb-type breakwater with the increase of relative width of the breakwater. 2）The differences in wave pressure at different measuring points are significant，and the wave pressure at the back plate of the comb-type breakwater is significantly higher than the wave pressure at the corresponding position on the headwind surface of the caisson-type breakwater.3）The water velocity in the comb cavity of the comb-type breakwater is significantly higher than that in the front of the caisson-type breakwater. 4）It is recommended to choose comb-type breakwater in the actual project.