The engine exhaust-powered refrigerating device recovers and converts exhaust heat of propulsion diesel engine of fishing vessels into energy for cold storage of fishes. It can improve fresh-keeping quality of the fishes and reduce the workload of the fishermen without increasing the energy consumption, which is in line with the national policy guidelines of energy conservation and consumption reduction. According to the target ship type and equipment parameters, a set of practical ammonia water absorption refrigeration system for fishing vessels was designed. The basic laws of thermodynamics were used to establish a mathematical model, analyze the parameters of each state point of the refrigeration system, and combine the energy conservation and mass conservation laws to calculate the whole system performance indicators. Finally, the variation of cooling capacity and refrigeration coefficient was obtained while the parameters such as generator heat load, solution pump and cooling water were changed. The device has been verified by multi-voyage operation on vessels, and the cooling effect is significant; however, the energy utilization efficiency of the system is low and needed to be improved by quantifying model parameter.