Abstract: A calculation model for matching the enthalpy parameters of three-wheel bootstrap cooling system was introduced according to the shortcomings of traditional method for matching thermal parameters.The model could simplify the wet cooling point matching process.And the thermal parameters of each system's status point was calculated by the model.The results show that,with the use of enthalpy instead of temperature as the state parameter for system matching,it's viable to simplify the calculation process.An optimal water equivalent ratio is found by system performance analysis;as the three-wheel power ratio increases,the compressor pressure ratio and turbine expansion ratio decrease.