Abstract: Non-metallic inclusions accumulated in the inner-side of slab for vertical bending caster were obserbed by on-line sulphur-print examination.The quantity or distribution and composition of inclusions is examined for such slab.It is concluled that the non-metallic inclusions accumulated in the inner-side of slab came from the blockage matrix of the immersion nozzle,which was entrapped into the liquid pool.Some improvements to avoid the includions accumulation are also presented.