Growing load demands, complex operating conditions, and the increased use of intermittent renewable energy pose great challenges to power systems. Serious consequences can occur when the system suffers various disturbances or attacks, especially those that might initiate cascading failures. Accurate and rapid identification of critical transmission lines is helpful in assessing the system vulnerability. This can realize rational planning and ensure reliable security pre-warning to avoid large-scale accidents. In this study, an integrated "betweenness" based identification method is introduced, considering the line's role in power transmission and the impact when it is removed from a power system. At the same time, the sensitive regions of each line are located by a cyclic addition algorithm (CAA), which can reduce the calculation time and improve the engineering value of the betweenness, especially in large-scale power systems. The simulation result verifies the effectiveness and the feasibility of the identification method.