This paper presents a static model for vulnerable lines identification in power grid, which uses the static comprehensive index to identify vulnerable lines in power systems. Based on the complex network theory, this method uses the DC flow algorithm to identify the important lines and the unimportant lines, which overcomes the vast calculation weaknesses of the previous algorithm. This paper presents the comprehensive vulnerable index to sort the important lines by the vulnerable importance. This index considers both the network structure and the running state characteristic of system, truly reflecting the influence of the power transmission of lines on the whole power system. The network efficiency percentage index is introduced and combined with the existing model to comprehensively reflect the system fault’s degree. The example simulation of The New England 10-generator 39- node system and the IEEE 118-node system proves that the model is valid and rational.