The invention provides a fixed electrode insulating mechanism of a sliding welding machine, wherein, the outer side of the fixed electrode is fixedly installed with a plurality of insulation boards; the spacing between insulation boards corresponds to a guide rib tank which is arranged on the fixed electrode; a base body of the fixed electrode is installed with a plurality of guide rib tank bodies which are provided with the guide rib tank; the back cut surface of the guide rib tank body is flush with the outer surface of the insulation board or is lower than the outer surface of the insulation board; or the two sides of the back cut surface of the guide rib tank body are provided with platforms; the insulation boards are arranged on the platforms to shorten as possible the distance between the outer side of the back cut surface guide rib tank of the guide tank body and the guide tank body, thus ensuring that when the electrode body is in a welding station, effective contact between aelectrode body and a hooping, a longitudinal rib, the fixed electrode can be realized; when the electrode is not in the welding station, the electrode body and the fixed electrode can be insulated effectively as the hooping is deformed and concaved downward by the acting force which is carried out by the electrode body on the hooping between two longitudinal ribs, thus eradicating the generation of heavy current energy wastage or even device burning-out by the direct contact between the electrode body and the fixed electrode.