The electric power communication network is special for the electric power network. Research on its essential vulnerability is advantageous to strengthen the toughness of the electric system. Take the complex network theory as the foundation, research on topology modeling, the basic parameters and network characteristic, take the service feature and the characteristics of the network structure into account, revising the traditional efficiency function which is regard as the target to measure the vulnerability of the network. Finally, take two actual electric power communication networks, the North China electric network and the Chengde network as example, analyze their characteristics. And then aimed at different failure modes, carry on vulnerability attack to the networks. According to the simulation results, vulnerabilities of the electric power communication networks will be found out; factors which have influence on the vulnerability of electric power communication network can be summarized.