Abstract: It is common that the square aquaculture tank has a large volume of lower velocity (dead volume) in the mariculture production. The arc angle instead of the right angle was used to optimize the structure of the tank, so as to improve the flow field uniformity of the square aquaculture tank and maintain a higher space utilization. In this paper, three-dimensional turbulent numerical models of the aquaculture tanks with different arc angle scales were established, and the flow field uniformity in the aquaculture tanks were studied by using computational fluid dynamics technology, the velocity distribution in the tanks were mainly analyzed, and the evaluation parameter UC₅₀ (uniformity coefficient) was proposed to discuss the flow field uniformity. The results show that: the ratio of the moderate velocity zone in the tanks with 0.2≤R/B(relative arc to width ratio)<0.4 are relatively higher compared with the square tank, and the flow field uniformity is significantly improved. The theoretical basis is provided for the design of square arc angle aquaculture tank in this paper, and the optimal parameters are supplied for the structure optimization of square aquaculture tank.