Abstract: As distinguished from the level fluctuation caused by bulging for hypo-peritectic steel，aiming at serious mold level fluctuation of thin slab continuous casting for non-oriented silicon steel，by means of researching the effect of the submerged entry nozzle clogging on mold flow field and analyzing the workshop data of accident operation and level curve，it was inferred that the main cause for level fluctuation was the submerged entry nozzle clogging resulted from a great deal of deoxidation products which had not been efficiently removed. The production practice at steelmaking plant of Bensteel indicated that mold level fluctuation range during non-oriented silicon steel casting had been dropped from more than±15 mm to less than±3 mm through some technical measures as controlling accurately blowing end-point oxygen mass fraction of molten steel below 800×10-6，reducing argon flow rate from 150-200 L/min to 40-50 L/min at the later stage of RH，and raising properly superheat to 25-45 ℃ of liquid steel in tundish.

Key words: non-oriented silicon steel, mold level fluctuation, submerged entry nozzle, clogging