In order to further remove the large inclusions, an electroslag remelting furnace with electromagnetic stirring is designed and the effects of external magnetic field and different electrical parameters on the cleanliness of electroslag ingot are studied. The gas content is analyzed by oxygen and nitrogen analyzer, and the morphology, composition and size of inclusions are observed and analyzed by scanning electron microscope. It is found that the oxygen content in ESR ingot increases obviously after electroslag remelting whether the external magnetic field is applied or not, but the nitrogen content decreased slightly. The oxygen content in consumable electrode increased from 0.0007% to 0.0052%, and the growth rate is as high as 7 times. However, the types of inclusions are basically unchanged, which are mainly composed of alumina, manganese sulfide, manganese sulfide oxide composite inclusions and oxides, among which alumina is the most. After remelting with external magnetic field, the diameter of the largest inclusion in the consumable electrode decreased from 89.6 μm to 12.1 μm in ESR ingot (1.1 kA/108 Gs), the proportion of small inclusions increases and the number of large inclusions decreases. However, excessive electromagnetic force is not conducive to the removal of large inclusions. When the remelting current is 1.5 kA and the magnetic induction is 108 Gs, the electromagnetic force is the largest, and the maximum diameter of inclusions is up to 30.6 μm which is larger than that in electroslag ingot without magnetic field. The increase of oxygen content after electroslag remelting is caused by air pollution and unstable oxides in slag. The electromagnetic force generated by external magnetic field increases the contact area between slag and metal, thus absorbing large inclusion.