Business expansion is an important work in the marketing and distribution management of power supply enterprises, it is of great significance for forming and maintaining a good distribution network structure, ensuring the power supply reliability of the distribution network and improving the utilization efficiency of the distribution network resources. At present, when setting up the power supply access plan, it is often based on the maximum load level of users, the timing characteristics of large user load are ignored, so there are a series of problems, such as the increasing of load point and peak valley difference. In order to further improve the precision of the expansion and installation of large user industries, a method of expanding user assistance is proposed based on load characteristics. Firstly, the load feature library of large users is established by fuzzy C-means clustering (FCM). Secondly, the load pattern recognition method is established by gradient lifting tree model. Then, a combined optimization model of power supply access is proposed. Finally, a typical example is given to verify the effectiveness of the proposed method.