A valve mechanism for a suction instrument or an irrigation instrument is disclosed, which comprises: a valve object； a first piston moveably disposed in the valve object； a second piston moveably disposed in the valve object； and a piston buckling unit disposed outside the valve object. When the first piston is pressed, the first piston moves downward and a first buckle on the first piston is fixed on a third buckle of the piston buckling unit to open a irrigating pathway； and when the second piston is pressed, the second piston moves downward and a second buckle on the second piston is fixed on another third buckle of the piston buckling unit to open a suction pathway.本發明之用於抽吸裝置及沖洗裝置之抽吸沖洗閥門機構，包括：一閥本體；一第一活塞，可移動的設於閥本體內；一第二活塞，可移動的設於閥本體內；及一活塞卡扣機構，設於閥本體外。其中，當施壓於第一活塞時，第一活塞係從上往下移動使得第一活塞上的第一卡扣件卡扣於活塞卡扣機構的第三卡扣件上，而形成一沖洗通路；當施壓於第二活塞時，第二活塞係從上往下移動使得第二活塞上的第二卡扣件卡扣於活塞卡扣機構上的第三卡扣件上，而形成一抽吸通路。
