In order to improve the heat transfer performance of micro heat pipes,a new type of micro heat pipe(GF) with capillary wick,which is made of fiber- sintered grooves with an external diameter of 8mm and an internalcavity diameter of 4.5mm,was experimentally investigated.Then,the heat transfer performance of GF2 and GF5,namely two types of GF respectively with the filling fiber length of 2 and 5 mm,was compared with that of thecomposite heat pipe (GA) fabricated by copper powder.The results show that GF is of better heat transferperformance.For instance,the wick porosities of GF2 and GF5 locally distribute and the average values respectivelyreach 71.6% and 76.3%.The maximum heat transfer power of GF2 is more than 140W,and,with an input powerof 20 ～70W,the evaporator,condenser and total thermal resistances are relatively low and keep unchanged respec-tively at about 0.04,0.03 and 0.07℃ /W.Moreover,with an input power of more than 70W,both the condenserthermal resistance and the total thermal resistance obviously increase,and the total thermal resistance of GF is stilllower than that of GA.It is also found that the evaporator temperature of heat pipe is closely related to the evapora-tor thermal resistance,and that the total thermal resistance varies in a trend similar to that of the condenser thermalresistance.