A dynamic mathematical model for simulating the coupled heat and moisture transfer through walls was proposed with variable material properties. Relative humidity and temperature were chosen as the driving potentials. The temperature and relative humidity and heat flux of wall surface were calculated under varying boundary conditions and compared with those without taking moisture transfer into account. The results show that without and with absorption and desorption processes, the wall interior surface temperature amplitude of the former case is lager than that of the latter, and the average difference temperature of two cases is 0.9℃. The phase change latent heat caused by absorption and desorption of wall surface takes up 27.5% of the total heat transfer quantity, which cant be neglected.