Abstract: Evaporative misting cooling system, which was controlled by jet, has been developed for open swine houses in South China .In this system air flow distribution greatly affects the efficiency of evaporative cooling and the livestock physiology . Various jets have different characteristics on air flow in local places where is been cooling . The air flow distribution was measured by heatglobe anemoscope. In the case of range of air flow that meets the demands of pigs, experimental analysis on performance of various kinds of jets was carried out according to the principle of welldistributed air flow . The experiment showed that the performance of circular revolving nozzle of the cooling system was excellent . The circular revolving nozzle should be chosen as the first consideration in designing the cooling system.