A method for testing heat pipes includes the following steps. A plurality of bar-shaped heat pipes having the same size is provided, and the heat pipes are deformed. The deformed heat pipes are placed in a temperature regulator, such that a temperature of the heat pipes is periodically changed between a first temperature and a second temperature. The heat pipes are then taken out of the temperature regulator. One end of each heat pipe is maintained at a third temperature by a thermostatic device, and a heat pipe temperature difference of two opposite ends of the heat pipe is measured. The heat pipes having the heat pipe temperature difference greater than a standard temperature difference in the heat pipes are marked.