As an important part of the national security system, energy security is of great importance to the construction of a modern and powerful socialist country in China. Based on the definition of energy security by the International Energy Agency, an evaluation index system of energy security is constructed from three dimensions:production guarantee capacity, import diversification degree and economic affordability. On this basis, analytical hierarchy process (AHP)-entropy weight method-improved technique for order preference by similarity to an ideal solution (TOPSIS) evaluation method are combined to obtain relatively fixed energy security index which is not affected by evaluation range and evaluation period. Through the comprehensive evaluation of energy security levels of China and the United States from 2015 to 2021, the change trends of energy security indices of China and the United States are obtained. The results show that China has vast improvement in energy supply guarantee capacity and energy consumption cost, and still needs to further improve China's energy production capacity, accelerate the construction of a new energy system, enhance energy self-sufficiency, expand the scale of international energy cooperation, reduce energy consumption costs, and ensure energy security.