Abstract: Capillary pumped loop(CPL) which with a flat type evaporator and two flat type wicked condenser was designed,fabricated and tested to study operation character.Methane was used as working fluid,and the flat type heater was used as heating source.Experimental(investigation) results were presented.The results indicate that the heat transfer rates and(evaporation) rates are changed with the heating loads variation.At high enough heat levels,the(evaporator) dries out and the system fails.For a range of power applied to the evaporator,the(system) presented reliable start-ups and continuous operation for several hours.With as variable heat flow,the CPL evaporator presents good heat adaptability.With wicked condenser,the system pressure oscillation was reduced largely,even more eliminated.