In order to accurately predict the indoor temperature and humidity distribution and dynamic change under the protection of multi-storey walls in cold and dry winter areas, the heat and humidity coupling transient transfer law of the whole building is studied. Based on the basic transfer theories such as dancy"s law, Fourier"s law and Fick"s law, the unsteady coupling transfer control equation of hot and humid air in the wall is adopted, and the temperature and relative humidity are taken as the driving potential, The unsteady state model of heat and moisture coupling transfer of integral building porous media wall is established. By focusing on two kinds of thermal insulation building materials: Graphite polystyrene board and EPS thermal insulation board, the heat and moisture coupling transfer and indoor temperature and humidity regulation of integral building with two kinds of walls are simulated and analyzed. The results show that the thermal insulation performance of EPS is better than that of graphite polystyrene board in cold and dry areas in winter; After 24h closed simulation, the indoor average relative humidity in the two cases are 38.00% and 36.50% respectively, and the indoor average temperature is 3.75 ℃ and 4.20 ℃ respectively; There is a nonlinear relationship between the relative humidity near the wall and the temperature in the center of the room. The research results can provide a reference for the design of building envelope in cold and dry areas in winter.