In order to maximize the energy extraction potential from the marine resource, the primary task is to improve the power generation efficiency of multi-unit turbine arrays. There are many factors that affect the power generation efficiency of hydro turbine arrays. This paper mainly studies the influence of the effects of array structure parameters on the flow structure of the near-wake flow field and the energy utilization. The numerical simulation results are compared with the experimental data to verify the reliability of the numerical model. The double-row staggered arrangement of the turbine array is selected, and the size of the array structure parameter, the horizontal distance Dx and the vertical distance Dy, is changed to calculate a series of working conditions. The analysis of the results shows that when the horizontal distance Dx is 2.5RD and the vertical distance Dy is 2RD, the energy efficiency of the turbine array will reach the highest.