Abstract: Abstract：The requirement of integration and heat dissipation of communication equipment and reserve battery in agriculturalbase station is getting higher and higher. High temperature affects the stability of server equipment operation which reducesthe comprehensive performance and service life of the equipment. In order to solve this problem, air conditioners with enoughredundancy need to operate continuously to ensure the normal operation of equipment. In order to maximize the use of naturalcold energy to reduce the huge energy consumption of air conditioners in winter and transition season, this research proposeda new type outdoor natural cooling air cooler (NCAC),which is composed of micro heat pipe array (MHPA) with serrated fins.The serrated fins are used to increase the air convective heat transfer area, and to enhance air disturbance and heat transfer.The parallel flow tube with tiny porous channel (PFT) is used to increase the water heat transfer area and contact area toreduce the thermal resistance. Under different outdoor environment temperature，the performance of NCAC under differentflow processes (downstream and countercurrent), inlet temperature, water fl ow rate and air flow rate were separatelyinvestigated, the heat transfer performance, temperature distribution, exergy efficiency and resistance characteristics were alsoanalyzed. Results showed that there was little heat loss between air and water side of NCAC, the heat loss rate was under 11%.The heat transfer performance of NCAC of countercurrent process was better than that of downstream process, the maximumheat exchange rate was 7.5 kW of countercurrent process, which is increased by 16.9% than that of the downstream process.For the NCAC of countercurrent process, the temperature distribution uniformity of the micro heat pipe array was better, andthe maximum vertical temperature difference in the condensation section of the heat pipe was 1.03 ℃ . The temperaturedifference between the evaporation section and the condensation section was 6.96 ℃ , the equivalent thermal conductivityreached to 1.72×104 W/(m · K). The pressure drop of the air side and water was at a low level, the maximum resistance of theair was 345.5 Pa, and the maximum resistance of the water was 8.92 kPa. The highest exergy efficiency researched 38.8%, theheat transfer capacity of NCAC still has large space for improvement. The average energy efficiency factor was over 17.2, theair cooler was in a better operation state. The experimental values of heat transfer factor and friction factor were obtainedaccording to the test of NCAC with serrated fins, the average value of comprehensive evaluation index was about 0.049,which increased by 36.1% compared to the plate fin heat exchanger with plain fins. The experimental results show that withthe increase of air flow, the increase of pressure drop is greater than the increase of heat transfer rate, and various factors mustbe considered comprehensively in the process of heat transfer enhancement. The research results can provide reference fordesign calculation, model simulation and practical application of air cooler used in base station.