Abstract: In this paper, through analyzing, the issue of comprehensive evaluation difference is turned into the question of the weight difference as to the differentiated evaluation of smart grid. In addition, the traditional Hall three-dimensional model is improved, the weight difference is elaborated into four-dimensional model, and the effects of different construction emphasis for smart grid caused by different sources in different regions on weights are taken into account. In the end, the construction evaluation of smart grid in different areas is studied according to decoupling index theory. Taking Beijing, Tianjin and Hebei power grids as examples, the application of model to differentiated evaluation of smart grid is discussed. The results show that the combination of four-dimensional model and the decoupling index can be used to reasonably evaluate smart grid construction in different regions.