Abstract: As the core functional unit of aquaculture platforms, aquaculture tank has advantages and disadvantages of its inlet and outlet configurations which have a significant impact on its internal flow field environment. To optimize the hydrodynamic conditions and enhance production efficiency, we established a 1:100 scale physical model based on a 300,000-ton-class rectangular aquaculture tank, employing Particle Image Velocimetry (PIV) for systematic hydrodynamic experimentation. By controlling key parameters including inflow rate and number of inlets, we quantitatively analyzed the evolution characteristics of flow field structures under different inflow conditions. Besides, we investigated the mechanisms by which various outlet structuresaffect vortex field characteristics within the tank. The results demonstrate that: 1) Inflow rate was the primary regulating factor for flow velocity. When the inflow decreased from 1 800 L·h⁻¹ to 900 L·h⁻¹, the high-velocity zone proportion decreased from 33.2% to 8.4%, the low-velocity zone expanded to over 65% of the tank volume, and the average velocity decreased by 52.89%, showing a linear correlation between inflow rate and average velocity. 2) Adjusting the number of inlets was more effective than flow rate modification in improving flow field uniformity. Reducing the number of water inlet decreased the DU₅₀ uniformity coefficient by up to 33.62% across different depths under identical conditions, and up to 39.68% across different conditions at the same cross-section. 3) Variation in the quantity and position of bottom outlets significantly influenced the vortex fieldcharacteristics within the aquaculture tank. When four outlets were installed at the bottom, the vortex effects on the water inside the aquaculture tanks could be effectively avoided.