In this paper, the optimal configuration of cooling, heating and power energy storage (CHPES) under the typical energy system architecture of commercial buildings is studied. On the basis of meeting the user's demand for electricity, heating and cooling, the configuration capacity and power of electric, heating and cooling energy storage are optimized with the goal of minimizing the total cost of equal annual value within the life cycle of the system. By dividing typical days, the variable dimension is greatly reduced and the solving time is shortened, so that the optimization model can be solved by the commercial solver. The numerical example shows that, CHPES can significantly reduce the equal annual cost of the system, and also promote the peak shaving and valley filling of the power grid.