Abstract: The width of columnar grain zone in as cast strips is mainly determined by the length of columnar grains at nip point. The columnar grain structure was simulated by FE-CA method in Calcosoft. The visualized morphology was obtained, and the calculation results fit the experimental ones well. By use of this model, the effects of process parameters on the width of columnar grain zone were studied. The results show that the width of columnar grain zone increases with increasing liquid steel surface height in the pool, but it decreases with the increase of casting temperature and casting speed.