A stochastic model for simulating the microstructure formation of twin-roll continuous casting pure aluminum during solidification process has been established based on a 3-D cellular automaton（CA）-finite element（FE）model in Procast package.Based on the finite element method（FEM）

macroscopic model of heat transfer calculation and a modified Cellular Automaton were established

in which the effects of solute redistribution

interface curvature

and preferred orientation were considered.Different Gaussian distribution of nucleation sites was adopted on the roll surface and in the melt

meanwhile

the modified KGT model related to partial undercooling was used to describe the growth kinetics of dendrite tip.The influence of processing parameters such as pouring temperature and average nucleation undercooling rate in the melt on the solidification microstructure of strip is evaluated.The simulation results show that the nucleation

growth

columnar-to-equiaxed transition（CET）

and microstructure evolution of free dendritic crystal can be predicted reasonably.