In order to prevent large-scale cascading outages effectively,a method based on comprehensive indicators to identify vulnerable lines was proposed.First,the branch removal distribution factor was modified,and the influence of power flow transferring direction was considered,so the branch removal vulnerability was proposed to reflect the removal vulnerability of the branch.Then,in view of the shortage of traditional betweenness,it was improved by the definition of power transmission distribution factor,and the transferring betweenness was constructed to reflect the fluctuation vulnerability of the line.By combining them as a comprehensive index to identify vulnerable lines,TOPSIS was utilized to rank the vulnerability of the lines,so as to screen out the vulnerable lines from the grid.Finally,with the New England 39-node system,Monte Carlo random simulation method was used to attack the selected lines,and the power dispersion level was calculated to reflect the change of the system safety.Compared with the related literature,the vulnerability of the selected lines and the rationality of the identification results are proved.