To　improve　the　performance　of　the　radiator　for　electronic　components,　the　indirect　thermosyphon　radiator　coupled　with　flat　heat　pipe　is　developed.　The　characteristics　of　this　compound　radiator　charged　with　methanol,　ethanol,　acetone,　water　and　R123,　respectively,　are　experimented,　and　the　influences　of　charging　rate　and　air　velocity　on　the　radiating　effect　are　discussed.　The　results　demonstrate　that　the　compound　radiator　have　nicer　performances　in　large　heat　flux　and　wide　range　of　heat　flux　relatively.　And　it　is　able　to　keep　the　surface　temperature　steady　no　matter　the　heat　flux　varies　smoothly　or　suddenly.　The　radiator　charged　with　R123　shows　better　performances　and　keeps　the　temperature　less　than　70　degrees　C　when　the　heat　flux　is　as　high　as　200W.　The　optimum　charge　rate　of　the　radiator　is　about　80%　when　the　heat　flux　varies　from　100W　to　140W.