An ash/wax removal apparatus for plastic pyrolysis process and the pyrolysis using the same is disclosed, in which the ash/wax removal apparatus comprises: an ash settling tank, having an wax guiding opening formed thereon, a top connected to a wax exhausting outlet of a degreasing tower and a bottom connected to an ash discharging pipe; an ash discharging valve, arranged at a position between the ash settling tank and an ash gathering tank; a wax guiding pipe, being configured for enabling an end thereof to connect to the wax guiding opening and another end thereof to connect to a pyrolysis device and composed of a plurality of tubes in a manner that one of the plural tubes is a return tube capable of connecting with other tubes by flanged pipe fittings through the two end of the return tube; and a wax exhausting valve, arranged at the exit of the end connecting to the pyrolysis device; wherein the ash gathering tank is positioned at a position corresponding to the ash discharging pipe; the length of the return tubes of different length are suitable to be adopted as the return tube of the wax guiding pipe with correspondence to the capacity of wax return.