Vulnerability of networks is not only associated with the ability to resist disturbances but also has an impact on stable development of the networks in the long run. In this paper, a new vulnerability evaluation based on fuzzy logics is proposed. To obtain the vulnerability of the networks, fuzzy logic is utilized to model uncertain environment. Therefore, this evaluation can be divided into two steps. One is to use a graph to represent the network and analyze the main properties of the network, including average path length, edge betweenness, degree, and clustering coefficient. The other is to use fuzzy logics according to the main properties. Namely, this step is to calculate deviations, design rule database, and obtain vulnerability. Two examples are given to show the efficiency and practicability of the proposed method at the end. Copyright © 2015 John Wiley & Sons, Ltd.