Abstract: In order to research the influence on the hydrodynamic characteristics of single-drain marine aquaculture tank with different double-inlet pipes distances, especially the velocity distribution of the bottom and near discharge outlets. The RNG k-ε turbulence model was applied to simulation the flow field in rectangular arc angle aquaculture tank , the computational fluid dynamics study is performed to analyze the impact of different layout positions under double-inlet pipes structure conditions on the flow field of the tank, and the fluid dynamics characteristics variables were adopted to analyze the complex the flow field in the near of sewage outlet. The results indicate that the position of the inlet pipe in the double-inlet pipe structure has a significant influence on the velocity distribution at the bottom of the tank; the double-inlet pipes at the arc angle is conducive to improve the hydrodynamic characteristics at the bottom of the tank.