The hydraulic retarder is an auxiliary braking device used in heavy duty vehicle. It generates braking forceby liquid damping effect and makes inertial energy into thermal energy of the transmission medium when the vehicleis in thedownhill. The traditional thermal management system of the hydraulic retarder dissipates the heat of transmission medium out of the vehicle directly, which causes a big waste of energy, meanwhilethe thermal management system components need to consume engine power.This study applies organic Rankine cycle (ORC)cooling system to meet the high power cooling requirements of the hydraulic retarder and recover waste heat energy from the transmission medium at the same time and then supply energy to the thermal management system, which could save the parasitic power of the engine and improve the comprehensive energy utilization ratio of the vehicle.Firstly, the hydraulic retarder heat generating model and ORC thermodynamic model are established based on a certain type of hydraulic retarder. The outputting power characteristics and the circulation flow rate of ORC are studied on the premise that the hydraulic retarder import and export oil temperature meet requirements. The variation of the waste heat recovery efficiency under different operating conditions of the hydraulic retarder is figured out. Finally, the system performance is evaluated while the recovery power and power consumption of the system are compared and analyzed.The result shows that the energy recovery system can meet the cooling demands of the hydraulic retarder. The recovery power of the system and the mass flow rate of Rankine medium are proportional to the heat power of the hydraulic retarder. With the increase of the speed and gear for the hydraulic retarder, its heat power increase and the energy recovery system recovered energy can be completely self-sufficient its energy demand underany operating conditions of the hydraulic retarder. Compared with traditional thermal management system of the hydraulic retarder, the system energy utilization ratio is higher and the economic benefits are remarkable.