In order to reflect the characteristic of sharp interface during the d endritic growth process, cellular automaton method is used to simulate the dendr ite evolution. In this method the different physical properties in both solid an d liquid phases are adopted to reflect the different heat_transfer rate. The simulated results show that there is solute micro-segregation between the two p rimary dendritic arms. In addition，the solute concentration gradient and temper ature ahead of the solid/liquid interface decrease gradually with increasing solidification time. Comparing the simulated radius of the dendritic tip with the theore tical radius, we obtain that the simulated results fit the theoretical radius well, and the deviation is less than 1μm.