The invention discloses a comprehensive energy system energy efficiency assessment method and device. The comprehensive energy system energy efficiency method comprises the following steps: constructing an integrated energy system model which comprises a renewable energy power generation module, a distributed combined heat and power generation module, a heat pump, a boiler and an electric refrigerator module, and input energy of the integrated energy system model comprises non-renewable energy power generation energy, renewable energy power generation energy and outsourced electric energy, andthe output is in a cold, hot and electric terminal energy form; constructing an energy efficiency assessment index system of the comprehensive energy system, wherein the energy efficiency assessmentindex system comprises primary energy consumption, primary energy utilization rate, primary energy consumption saving rate, renewable energy consumption rate and efficiency; and establishing a scene energy efficiency assessment method, determining the weight of each assessment index, and combining each assessment index with the weight to obtain a comprehensive assessment result of the scene. For the comprehensive energy system energy efficiency assessment method, the comprehensive energy efficiency of the whole year of the system can be quantitatively assessed, so that quantitative energy efficiency numerical values are provided for selection of specific project schemes of the comprehensive energy system, verification of benefits and optimization of operation strategies.