Abstract: Flexible load participating in scheduling can contributes to peak-load shifting, optimize load curve and reduce the cost of system. Considering translational load, transferable load and reducible load, a flexible power load model was established. According to the fuzziness of user’s perception on the temperature a flexible thermal load model was built. Adopting mixed integer linear programming method and taking minimum economic cost and least primary energy consumption as the objectives, the configuration of the integrated energy system was optimized to obtain the optimum capacity of each equipment and its output in each time-interval. Results of calculation example show that by means of scheduling flexible electrical load and flexibly adjusting indoor temperature, the consumption of renewable energy sources can be promoted, the electrical load curve and the thermal load curve can be optimized, thus the installed capacity of wind turbines can be increased and the capacities of both gas turbines and heat storage tanks can be reduced, the economy of system can be improved, besides, the consumption of primary energy source can be reduced and the penetration rate of renewable energy source can be increased.