Considering that thermal storage characteristics of building are not fully utilized in the optimal scheduling of the integrated energy system on the user side, a gas turbine-based combined cooling, heating and power (CCHP) system is established, and a building heat transfer model is established by taking factors such as radiation distribution, heat transfer in the building envelopes and indoor air into account. The building energy storage is involved in the optimal scheduling process by setting the temperature comfort range. At the same time, the CCHP system in four scenarios are optimized with the goal of minimum total operating cost, the operating costs are calculated to be 187.01 $, 316.52 $, 191.55 $ and 319.13 $ respectively. The results show that the envelope can not only insulate the heat but also store the heat. The envelope and the indoor air together form the building energy storage, which can participate in the thermoelectric decoupling or cooling demand adjustment according to heat demand and electricity price, and making full use of the building energy storage characteristics can effectively reduce operating costs.