A simplified dynamic heat transfer model with different heat capacity and thermal resistances (2R1C, 4R2C and 6R3C) of planar phase change materials is proposed. The RC parameters of the simplified model are identified by genetic algorithm (GA). The accuracy and applicability of different simplified models are analyzed. The results show that the identification parameters are less and the application is better for 4R2C model with good accuracy. Compared with the results of numerical model,the average difference of the surface temperature is less than 0.3℃, and the average relative difference of the heat flow through the left and right surfaces are respectively about 10% and 5%. The accuracy and applicability of the simplified dynamic model is reasonable under the different boundary conditions. The computational efficiency of the simplified model is much higher, for the computational time of the simplified model is less than 0.1% of that needed by the numerical model.