Heat　pump　thermal　control　system　is　one　future　direction　of　development　of　space　radiator　heat　rejection,　condenser　is　an　important　component　in　the　system,　its　condensation　performance　is　essential　on　the　work　of　the　instruments.　In　this　paper,　a　double　fin-tube　radiator　was　designed　for　the　heat　pump　thermal　control　system　as　a　condenser,　and　the　corresponding　mathematical　model　was　established.　The　impact　of　fin　geometry　on　the　radiation　characteristics　of　heat　rejection　was　analyzed.　The　optimal　fin　width　was　calculated　under　the　optimal　heat　rejection　per　unit　area　and　the　optimal　mass　of　fin-tube　radiator.　©　All　Rights　Reserved.