Abstract: The pumped loop heat pipe heat exchanger unit consumes low energy and has a high energy efficiency ratio( EER). For a better application of small data centers,this paper studied the operating performance of a pumped loop heat pipe heat exchanger unit that was used in a small data center. The operating characteristic curve was fitted and the result showed that EER varied with outdoor temperature and then an energy saving analysis was made according to the curve fitting. Results show that in the transitional and winter seasons,the pumped system can meet the heat load and get a good energy saving effect when the outdoor temperature is below 15 ℃,and it can achieve at least 36. 57% energy saving compared with the way of using air-conditioning for cooling.