Crushed ice, which is usually used on domestic fishing vessels to keep the fish fresh, has poor heat transfer effect, and its sharp corners often pierce the fish, resulting in a poor freshness retaining effect. On the contrary, the ice slurry has a good application prospect in fish freshness retaining due to its good fluidity and large cold storage density. Based on the Eulerian two fluid model of dynamics theory, this paper studies the flow and heat transfer characteristics of ice slurry by using the method of combining particle flow with heat and mass transfer model. The flow and heat transfer between the ice slurry and the fish in the square tube is calculated and studied based on the verification of the calculation model by using the literature data. The heat transfer performances between ice slurry and square fish in horizontal square tube at different inlet volume fractions and different flow velocities are compared and analyzed. The results show that the distribution of ice particles is the main factor affecting the heat transfer between them and the surface of the fish. With the increase of the inlet volume fraction of the ice particles, the heat flux of the upper surface and the side of the fish increases. With the increase of the inlet volume fraction of the ice particles, the distribution on the surface of the fish tends to be uniform. In addition, it is found that increasing the flow velocity can increase the volume fraction of the ice particles on the surface of the fish, thus increasing the surface heat exchange.