Abstract: In this paper, solidification process of laser pool for composite coating system is studied, using numerical technology. The results demonstrate that solidification process may be divided into two stages: quasi-state stage and accelerating stage. At quasi-state stage, the depth and radius of laser pool have small changes, but the highest surface temperature and velocity of molten pool decease rapidly. At the accelerating stage, those are on the contrary. Because of highly overheating in upper molten pool, post molten phenomenon is produced in down molten pool, during solidification quasi-state stage. The key factors to produce post molten region are the overheating and the latent heat released during solidification process in upper molten pool.