Combined cooling, heating and power systems realize an energy cascade utilization that has high overall energy efficiency and economic benefits. A typical combined cooling, heating and power system model was built, and an optimization method based on an exhaustive search method and a cost-oriented index was proposed to determine the optimal system configuration. Further, based on a residential building in Weifang city, an economic comparison of combined cooling, heating and power system was analyzed, by following electric load and following thermal load strategies. As a result, there is an economic difference of approximately 1 yuan per unit of energy supply area, with 58 yuan for following thermal load strategy and 57 yuan for following electric load strategy. Its originality lies on the introduction of an estimation method that could quickly and easily determine the optimal rated capacity of devices for combined cooling, heating and power system. Moreover, the effect of building features on the cost of combined cooling, heating and power system was analyzed in terms of the distance between the system and buildings, as well as the building floor area ratio. It indicates that combined cooling, heating and power system displays a better economy for a larger area, and following electric load strategy is more benefit for the system. Finally, the feasibility of solar thermal utilization in combined cooling, heating and power system was analyzed. The results show that the solar collectors only provide economic advantage for a smaller energy supply area, without coupling with combined cooling, heating and power system. To some extent, it is contrary to the current view of promoting solar utilization.