Abstract: The effect of heat source location on the heat transfer of an axially grooved heat pipe was investigated. An abnormal startup process was observed when the heat source was located at a position on the heat pipe near the stationary level of the working liquid. The work temperature of the heat pipe showed a temporary increase during the abnormal startup process. The highest temperature in the abnormal startup process was influenced by the heat source location，heating rate and liquid volume in the heat pipe. When the heat source was located at different positions on the heat pipe below the stationary level of the working liquid，the working temperature，the startup process and the maximum heat load of the heat pipe were different.The heat pipe could not work normally,when the heat source was located on the heat pipe above the stationary level of the working liquid by a certain distance.