Managers and planners attach importance to evaluating the whole size and controlling the gross constructing investment in the distribution network. To solve this problem

the authors have established a set of indexes system composed of size indexes and influence factors. And a series of systematic methods indispensable for estimating the constructing size of distribution network is presented to enable the classification of districts to be evaluated. The method proposed in this paper includes the following essential processes. Firstly

it calculates the numerical value of the gray correlation degree between the influence factors and size indexes used as indicators to evaluate the influence degree of influence factors vs. size indexes. Secondly

it builds up a characteristic vector space described by the above gray correlation degrees

and then describes the similarity degree between all districts to be evaluated in the distribution network using the distance over the characteristic vector space. Finally

it completes the classification of districts using the fuzzy clustering method. The simplicity and effectiveness of the proposed method is verified with an actual application.