The research on the influence law of time lags and decrement factor （TLDF） characteristics for different exterior wall combinations on building peak heat transfer is of significance to reduce the peak heat transfer load and the capacity of air-conditioning system. Taking a case building as an example， EnergyPlus and orthogonal experimental design methods are used to study the change law of the TLDF characteristics and peak heat transfer cooling load of different exterior wall combinations. The results show that the external disturbance of each wall combination has different TLDF characteristics， resulting in a difference in the peak cooling load， and the maximum difference is 11.8%. An optimization method for the peak heat transfer of exterior walls is proposed， based on the fact that the peak heat transfer of different exterior walls appears at different times and can reduce the total heat transfer peak value after superposition. The peak shifting indicator （PSI） is introduced into the inner surface temperature relation of each facing wall to adjust the time lags of the wall combination. The PSI is introduced into the inner surface temperature relation of each facing wall to adjust the time lags of the wall combination. The PSI and the wall total heat transfer peak value are taken as design variables and objective functions， respectively. The optimal time lags of each facing wall are obtained by optimizing the solution， and then the optimal wall combination is obtained. The method is used to calculate the case building， and the results show that the total heat transfer peak value is reduced by 19.1% after the optimal combination of the exterior wall.