Abstract: The inclusions in P92 steel were analyzed by OM, SEM and EDS, and the effect of composition change of cored wire on the modification of inclusions in P92 steel was studied. The results show that compared with the traditional Si-Ca wire, the composite cored wire has stronger deoxidation ability and can change the morphology and distribution of inclusions in steel. When the traditional Si-Ca wire is used, the inclusions in the steel are Al2O3 particles with irregular shapes; when the magnesium-containing composite cored wire is used, the inclusions are MgO-Al2O3 particles with approximate spherical shapes, and the size of the inclusions becomes smaller with the increase of Mg content in the cored wire.