Abstract: With mathematical simulation,the influence of process parameter,such as submerged nozzle structure、flow control switch、outlet angle、submerged depth of nozzle、width and thickness of mold、argon blowing etc on fluid flow in mold,fluctuation and primary slab shell are studied in high speed continuous casting.The result showed that effect degree for process parameter to liquidity of steel in mold under high speed are larger than low speed.The fluctuating of steel level become severity,depth of impingement increased.Then the quality of slab will be deteriorated with the speed of slab continuous casting increaseing.The optimizing of the submerged entry nozzle and matching for mold and electromagnetic brake are important to high speed slab continuous casting.Flow beam of molten steel in mold under high speed has severe effects for primary slab shell, it's also one of cause for leakage of molten steel.