Abstract: An integrated energy system based on source side of thermal power plant was proposed,which takes thermal power units as the core, couples multiple renewable energy inputs such as biomass gasification, garbage gasification and dried sludge at the input end of the system, and supplies multiple energy products such as colding, heating, steam and electricity at the output end. By coupling the thermal balance model of the power plant with the renewable energy model and cooling/heating system model, an optimization configuration method was established with efficiency and economy as the objectives. The following two types of optimization logics, input optimization and output optimization, were adopted to analyze the impact of the main operating parameters of the integrated energy system on the economy and efficiency optimization goals from the input and output ends of the system. Results show that integrated energy transformation has positive significance for current thermal power plants.