The suitability of water temperature in the water tank of aquaculture ships is essential for the growth and survival of aquaculture species. The aquaculture ship raises salmon and trout by pumping cold water from cold water masses. For monitoring water temperature effectively by deploying temperature sensors scientifically, this study constructed 3D heat-flow-solid consolidated model and then conducted numerical simulation analysis on different flow velocities and thickness of insulation layer. The study results indicate the thickness of the insulation layer does not influence the spatial distribution of water temperature significantly and also is not correlated with the mean temperature of a stable state, but the thicker insulation layer can slow down the heat input from outside and is conducive to maintain the water temperature of aquaculture tank. The change in water temperature is not significant between the 30cm and 40cm insulation layer, hence 30cm insulation layer made by rigid polyurethane heat preservation materials is recommended. Three different inlet speeds (4 m/s, 5 m/s, 6 m/s) affect the cooling speed of the water, but do not affect the spatial distribution of water temperature significantly. We found temperate sensor can monitor the water temperature effectively by deploying it in the vertical, central profile distant from the outlet and near to water surface.