Abstract: The differences of stainless steel and carbon steel were discussed in component, solidification character, performance under high temperature based on the function of [Ni], [Cr], [Ti] in stainless steel. The mechanism of major defects on stainless steel billet was investigated, which included surface depression, crack, slag inclusion. The effect of molten steel purity, casting temperature, performance of protecting slag, oscillation and liquid level control of mold in continuous casting on surface defect was studied importantly. Combining practical production of 0Crl8Ni9, 2Crl3 and Ti-stainless steel, the measures against depression, crack, slag inclusion and deep oscillation mark which can't be smoothed easily are put forward.