Phase transition cooling (PTC), using the absorbed latent heat during the melting of phase transition cooling medium to cool and solidify alloys in the process of casting, is a new casting technology. Specimens of pure Al were prepared by this method in the paper. The temperature field of the casting was simulated with Ansys software. Parameters which affect the process of solidification were simulated too. The results showed that the pouring temperature of melt and the amount of phase transition medium have great effect on the process of solidification.