To master the heat transfer rule of phase change material(PCM) wall, two kinds of hollow boxes was made with different material, one was made of pure EPS granule,the other one was made of EPS and PCM, temperature of cavum was measured during thermal translation process experiment. The hollow boxes was separated into 4 nodes finite element, the experiment time was divided into finite time point, the diathermanous process of boxes was simulated by finite element software system. The result indicated that simulation process by computer was inosculated with experiment, there was obvious temperature flateform during heat transfer of PCM wall, duration of different direction of phase change process was different, during ascendant process and descent process, change rate and distributing characteristic were contrary on the two sides of phase change point temperature.