The gas engine driven heat pump(GEHP)is a new style air condition system which is composed of the gas engine driven heat pump (GEHP), the primary heat exchanger, the second heat exchanger, the water spraying chamber and some auxiliary equipments such as fans, water pumps, etc. When the GEHP operates in summer, the air which is cooled and dried by the primary heat exchanger is reheated by the second heat exchanger, then the air is transmitted to the AC room to keep the temperature and the humidity. When the GEHP operates in winter, the air which is heated by the primary heat exchanger is reheated and humidified by the water spraying chamber, then the air is transmitted to the AC room to keep the temperature and the humidity. The mathematic model including the primary heat exchanger model, the second heat exchanger model, the water spraying chamber model, the mixed air model, the GEHP model, was used to research the GEHP system. The primary energy ratio for air condition (PERx) was defined to evaluate the performance of air condition. Results from the analysis show that the gas engine driven heat pump can save more energy than the electricity engine driven heat pump. The GEHP with the wet processing can be used in more areas than the common GEHP.