Abstract: A super structure for total site energy integration is established considering steam level factors， where all possible topology of heat transfer and exchange among site heat sources, utility system, steam and site heat sinks, are described. Based on the super structure, a mixed integer non-linear programming(MINLP) model is established for total site energy integration. Steam levels and flow rates of high pressure(HP), middle pressure(MP) and low pressure(LP) are obtained by solving the model using line-up competition algorithm(LCA), resulting in better efficiency of energy integration. The examples show that the energy integration results obtained by this method are more reasonable than those without considering steam level factors.