The classification of distribution network power supply area is an important fundamental work for the planning and construction of distribution network which will directly affects the scale of investment for the construction of power grid. The scientific and reasonable classification of the power supply area can help to make a differentiated aim and plan of distribution network; meanwhile, it can also meet the requirements of reliability and economy so as to prolong the life-cycle of distribution network. Taking three factors into thorough consideration, namely, the development level, construction level, and load level of all the areas, this paper gives a complete index system for the classification of power supply area. According to the relevant data, the authors use the grey polycategory method of the improved whitenisation weight function to classify the area of distribution network. In the process of this, the index weight is obtained by the comprehensive application of AHP and entropy weight, which can prove that the method from this paper is useful according to the result of the classification of power supply in a certain city in Henan. The division of the distribution network power supply area is a key issue in distribution network planning. Due to the actual situation of distribution network in China varies greatly. If the construction is carried out according to a unified standard, it will result in economic and technically unreasonable situations such as inefficient use of equipment assets and serious waste. Scientific and rational distribution network planning is the basic basis for the construction and transformation of power grids, and it is also an important prerequisite for safe, reliable and economical operation of power grids. The division of scientific and reasonable power supply areas for distribution networks and the provision of guiding opinions based on the district results are conducive to improving the investment decision-making level and investment efficiency of power grid planning.