Abstract: The microstructural appearances of the slag of stainless steel electrodc and their influence on slag detachability have been studied by means of SEM., XRD. and optical microscope. It has been known that the dire ctivity and continuity of microstructural appearanccs of the slags are important factors of slag detaching; the free oxides and the fine crisscross structures are mainly cause of the slagadhesion on the weld.