The thermal characteristics of the copper – water、micro-grooves axially flat heat pipe,including the startup features of the heat pipe,charge ratio,inclination and the heat of condensation on the ability of heat transfer performance were researched experimentally.The results showed that: heat pipe has a good startup features,its best charge ratio is 1.3,heat pipe heat exchanger can be assisted be gravity,the heat transfer performance improved,the improving of condensation ability can effectively raise the heat of the heat transfer performance.