A deep study is given to smart grid comprehensive evaluation system. According to the smart grid characteristics and basic properties in China, a smart gird index system is built from the aspects of strongness, reliability, efficiency, economics, environment and interaction. Based on the calculation of Entropy-ANP combined weighting and improvement on two evaluation methods, a new method of comprehensive evaluation of the smart grid and its computational model are proposed. The principle, theory and procedure of this method are comprehensively studied. The overall computation and analysis system including index selection, weight calculation, model construction and evaluation results analysis are established. Applying the method to the case, it shows that the method could offer the valuable reference for adjusting the smart grid plan, making the smart grid roadmap, judging the implementation effect of smart grid construction.