In order to consider the impacts of distributed generation (DG) output and load uncertainty in distribution network planning, a fuzzy programming approach is proposed. Triangular fuzzy numbers are used to describe the uncertainty of DG. Based on credibility theory, the network planning model of distribution network is established. Moreover, a rapid spanning tree algorithm is presented to form the initial network configuration of under-planning system. Genetic algorithm (GA) is then used to adjust and optimize the initial network configuration and finally get the optimal one. The effectiveness of the proposed approach is proved through case simulation. This work is supported by National Natural Science Foundation of China (No. 61074046 and No. F030107) and Science and Technology Project of Hubei Electric Power Company (No. 52153814000D).