Abstract: For the variation of inclusions in the surface layer of IF slab,the size,quantity,distribution,composition and source of inclusions were investigated by means of total oxygen and nitrogen content analysis,optical microscopy,scanning electronic microscopy （SEM） and energy dispersive X-ray spectroscopy （EDS）.The results show that the amount of inclusions at the position of 3~4 mm from the inner arc surface is the highest,reaching 9.2 per mm² at 3 mm inner the surface and 8.8 per mm² at 4 mm inner the surface,while the quantity of inclusions ranges from 5.1 to 6.8 per mm² in other positions.The distribution of inclusion in the width direction is random.The majority of surface layer inclusions are Al₂O₃-TiO_x and Al₂O₃ whose size are mainly less than 20 μm,which accounts for 84% of the total amount of inclusions.