Abstract: In contrast to the logarithmic distribution of the flow velocity in the open channel section, the cross-section velocity in sea area of channel island presents complex distribution characteristics because the uneven sea bed has a great influence on the distribution of the flow field in the sea area. Through the indoor model test, it was found that the vertical velocity in the turbulent sea area of the channel island was in the form of a quadratic parabola, and then through the analysis and calculation, the turbulence velocity distribution formula was put forward, which takes the equivalent slope as the main factor. The calculation results of the formula were in good agreement with the field measured results, and the correction coefficient of the flow load calculation based on the parabola distribution pattern was also given. The study can be used as a reference for the engineering structure design in the sea area of channel island.