Abstract: Using water and ethanol as the working fluids,the effective thermal conductivity of three kinds of capillary wicks in dry,water-containing and ethanol-containing states were obtained under different heat loads.It was found that the effective thermal conductivity of the three dry capillary wicks increased with the average temperature of the capillary wick.The effective thermal conductivity of zirconia and 3D-printed titanium alloy wicks in both water-containing and ethanol-containing states increased first and then decreased with the increase of the average temperature of the capillary wick,and finally tended to its own thermal conductivity.Under the water-containing state,the effective thermal conductivity of the silicon nitride capillary wick increased first and then decreased with the increase of the average temperature of the capillary wick.Under the ethanol-containing state,the effective thermal conductivity of the silicon nitride capillary wick did not change significantly with the increase of the average temperature of the capillary wick.