Ventilation　is　an　efficient　method　to　improve　the　leakage　safety　of　R290.　In　this　paper,　a　novel　integral-type　fresh　air　air　conditioner　is　proposed.　Compared　with　conventional　air　conditioner,　it　improves　leaking　safety　and　indoor　air　quality.　Moreover,　it　has　a　potential　to　recover　heat　from　exhaust　air.　A　green　house　was　built　to　simulate　a　full-scale　living　room,　and　the　influences　of　operation　mode,　diameter　of　leakage　hole,　supply　air　wind　speed　on　leakage　safety　were　experimentally　researched.　Results　show　that　the　diameter　of　leakage　hole　has　an　overwhelming　influence　on　the　concentration　distribution　of　R290.　The　closer　to　leakage　point,　the　higher　the　concentration　of　measuring　points.　Under　fan　mode　condition,　leakage　hole　diameter　within　1　mm　is　basically　incapable　to　cause　the　risk　of　flame　and　explosion　in　indoor　space.　Under　heating　mode　condition,　indoor　area　is　generally　safe　except　for　part　of　supply　air　outlet　right　below　the　leakage　point.　Moreover,　the　novel　air　conditioner　has　a　ventilation　flow　rate　of　30m3/h,　which　plays　a　remarkable　role　in　promoting　the　leakage　safety　of　flesh　air　air　conditioner　by　decreasing　the　leaked　refrigerant　concentration　at　a　rate　up　to　23%LFL/h.　This　paper　provides　reference　for　developing　fresh　air　air　conditioner　with　flammable　refrigerants　and　the　design　of　optimum　wind　speed　of　supply　air.