In　this　work　the　effect　of　argon　filling　ratio　and　air　space　thickness　on　the　heat　transfer　coefficient　of　double-glazing　was　studied.　The　heat　transfer　coefficient　of　double-glazing　was　measured　by　heat　flow　meter　method　(based　on　standards　ISO10291,　ISO　10292,　ISO8301　and　DIN　EN　12939),　during　this　process　the　testings　of　argon　filling　ratio　and　emissivity　of　coated　glass　surface　were　involved.　For　the　thermal　performance　of　double-glazing,　the　influence　of　various　factors　on　heat　transfer　coefficient　was　analyzed.　The　comparison　was　conducted　between　coated　double-glazing　(one　glass　pane　coated　with　low-emissivity)　and　non-coated　double-glazing.　Within　the　thickness　of　air　space　in　the　range　of　9-18　mm,　the　higher　the　air　space　thickness,　the　higher　the　filling　ratio　of　argon　gas,　the　better　the　thermal　insulation　performance　achieved.　Under　the　same　gas　filling　ratio,　the　heat　transfer　coefficient　of　coated　double-glazing　(emissivity　is　0.13)　which　is　much　lower　than　that　of　non-coated　double-glazing,　can　effectively　meet　the　requirement　of　building　energy　efficiency　in　China.