Abstract: The field studies reported here compare the performance of three ventilation styles with drip cooling system for relieving heat stress of farrowing sows under warm and humid production climate in southern China. The comparative system styles include: 1)tunnel ventilation with vertical head-zone ventilation; 2)tunnel ventilation(TV); 3)horizontal air mixing(HAM) when TV and HAM were used to create an air velocity of 0.51m/s and 0.40 m/s respectively. Body temperature(BT) and respiration rate(RR) of the sows were used to evaluate the efficency of the systems. The result indicated that tunnel ventilation with drip cooling provides the most cost-effective cooling scheme, the average BT and RR were 38.99 ℃ and 45.4% respectively under the inside air temperature of 31.5 ℃ and relative humidity of 82.5%,and the total electric energy use of 2.0 kW·h. The inside temperature shreshold for operation of drip cooling is 29 ℃; The inside and outside ammonia concentrations were within the limit.