Abstract: A gasification furnace is provided. The gasification furnace includes an outer shell having an outer shell inlet formed at a top of the outer shell and an outer shell outlet formed at a bottom of the outer shell; an inner shell having an inner shell inlet corresponding to the outer shell inlet, and an inner shell outlet corresponding to the outer shell outlet, and being fabricated by a membrane wall having a cooling water inlet and a cooling water outlet; a nozzle; a lower shell having a slag exhausting port and a gas discharging port; a cooler having a cooling passage formed therein, a cooler water inlet, and a cooler water outlet; a positioning member disposed between the inner shell and an inner bottom wall of the outer shell; and a gas guiding pipe defining an upper end connected with the cooler, and a lower end extended downward.