The invention relates to a backbone network optimization method of a high-proportion renewable energy source electrical power system so as to consider the effect of high-proportion renewable energy ina backbone network of the electrical power system and the influence on the electrical power system. The basic implementation process comprises the following steps: inputting topological structure andelectrical characteristic parameters of the electrical power system; calculating the relative importance degrees of load nodes, wind power plant nodes, photovoltaic power station nodes and conventional unit nodes; adopting an improved entropy weight-ideal solution to solve the relative importance degrees among the different types of nodes; adopting a staged backbone network to construct a strategy, optimizing the load nodes as a main task in a first-stage model, and adopting a colony algorithm for solution; optimizing power supply nodes as a main task in a second-stage model, and adopting thecolony algorithm in combination with a greedy strategy for solution. The core backbone network optimized and obtained by the method can guarantee power supply for important loads, and has relativelyhigh intermittent energy permeability and utilization rate.