The utility model provides a closed three -roller air cushion conveyer, casing one side sets up the feed inlet, its opposite side sets up the discharge gate, the setting of initiative cylinder is in the casing of discharge gate one side, driven cylinder setting is in the casing of feed inlet one side, the initiative cylinder passes through the belt with driven cylinder and is connected, be provided with the air intake on the casing, along the belt direction of advance, be provided with a plurality of oblique bearing rollers and flat roller on the casing, ganged two oblique bearing rollers and flat roller -Offset, be provided with the air chamber on the casing bottom plate, the air chamber is arranged along casing length direction, the air intake passes through pipeline intercommunication air chamber, be provided with the venthole on the casing bottom plate, the venthole corresponds the belt bottom surface. The utility model discloses a set up blast apparatus in the bottom of airtight casing, blow afloat return belt through blast apparatus when the conveyer belt return stroke, form the air cushion between the bottom surface in return stroke conveyer belt and casing to prevent the friction of the interior bottom surface of return stroke conveyer belt and casing, guarantee belt life, reduce the conveyer energy consumption.