A series of experiments based on a flat loop heat pipe under low-power have been conducted in this work. It is found that the LHP can start up unfailingly under low heat power (Q = 6W) and its thermal resistance is rather high in some cases of low-power. With the thickness of the sintered capillary inter-layer increasing, the performance of start-up in the LHP becomes better because heat leak to compensation chamber is reduced and the temperature difference between compensation chamber and the evaporation room is increased. When compensation chamber in the LHP has a heat sink installed, the temperature difference and pressure difference between compensation chamber and evaporation room are augmented. As a result, it is beneficial to the improvement of start-up characteristics. (C) 2010 Elsevier Ltd. All rights reserved.