For the ecological needs，a hydrodynamic environment with specific requirements needs to be created in the ecological reef group，and the inside structure cannot be blocked. This is realized by the reasonable layout of reefs under the action of waves in the siltation-type intertidal zone. For three layout patterns of grid surfaces aligned facing the waves，hollow surfaces aligned and staggered facing the waves，cross-section physical model tests are conducted to study the flow pattern and velocity distribution in the ecological reef site. The results show：1）Under the action of waves，the flow fields inside and outside the reef structure are all three-dimensional，and the velocity attenuation at each point in the reef group is generally uniform. 2）The velocity of hollow surfaces aligned facing the waves attenuates to 0.5-1.0 m/s under normal wave conditions，which well meets the requirements of the flow velocity in the ecological reef site.