On the one hand, the refrigeration using the tail gas of the main engine can provide the required cooling capacity for the freshness preservation of the fishes; on the other hand, it can save a lot of energy consumption while reducing the temperature of the tail gas emission as well. To clarify the process of waste heat absorption refrigeration of the main engine is helpful to provide necessary reference for fishery development, environmental protection and energy conservation. For the tail gas absorption refrigeration device of main engine on fishing vessel with 10 kW target cooling capacity, the chemical process simulation software Aspen Plus is used to establish a simulation model to analyze and calculate the ammonia flow in the refrigeration process of the device, and obtain the performance parameters of the solution pump and the cooling pump. During the process, it is found that pure ammonia precipitation is a direct factor affecting the cooling capacity, but it is also affected by the heat load of the generator and the power of the solution pump. By controlling the power of the solution pump, the influence of heat load fluctuation of the generator on ammonia circulation can be reduced, and the cooling capacity of the system can be stabilized; for the simulation model, the optimal refrigeration effect can be achieved when the flow of the solution pump is in the range of 355-455 kg/h; smooth removal of heat in the absorber can guarantee the system refrigeration cycle operation.