There are many uncertainty factors which influence the economic evaluation of distribution network. Traditionally, the probability analysis method and fuzzy mathematics method are adopted for solving the uncertainty problem in the analysis of economic evaluation. However, it is difficult to obtain the membership functions and probability distribution functions of uncertainty factors. In this paper, a new solution, namely a modified DEA model which is applied to the economic evaluation of distribution network is studied and is extended to the interval case, in order to deal with uncertainty. A whole process of modified interval DEA is demonstrated step by step. To indicate the proposed method, a worked example is performed on a test economic evaluation of distribution network. The result confirms that modified interval DEA method can get more discriminative efficient DMU, in an unprecedented flexible manner, much more useful information than traditional analysis. It provides an efficient and flexible evaluation tool for the power system planning, engineering and operations.