The invention discloses a door closing mechanism for a hydrocarbon cleaning machine. The door closing mechanism comprises a machine body, a furnace door, a moving mechanism and pressing mechanisms. The machine body comprises a door frame and a sealing structure arranged on the door frame, the door frame is of a plate-shaped structure with an opening, and the furnace door is located on the door frame. The moving mechanism comprises guide rails fixed on the door frame, a frame sliding along the guide rails and a first linear driving mechanism which drives the frame to move, the frame is located on the furnace door, and the frame is connected with the furnace door through a pin hole structure. Each pressing mechanism comprises a second linear driving mechanism, a connecting plate, a sliding rod and a cam, wherein sliding rails are arranged on the frame, the two ends of the sliding rod slide along the sliding rails, the second linear driving mechanism is fixed on the frame and drives the connecting plate to move, the sliding rod is fixed on the connecting plate, the cam is arranged on the connecting plate in a rotating mode, and the cam butts against the furnace door. By reasonably arranging the frame, the moving mechanism and the pressing mechanisms, the furnace door of the hydrocarbon cleaning machine can keep airtight under the positive pressure, ordinary pressure and negative pressure, and solvent leakage is avoided.