For the self-anchored suspension bridge with long span and complex structure, based on the finite element analysis, combined with the bridge load test, this paper makes a detailed analysis of its stress characteristics before damage and damage characteristics after damage, and on this basis, for the main vulnerable components of the main girder, selects a variety of identification methods based on the existing dynamic damage identification methods for comparative analysis, and finally determines an effective method suitable for bridge girder damage monitoring according to the identification effect of each method. For the main girder of vulnerable components of self-anchored suspension bridge, according to the mechanical characteristics of each section and the position relationship with the assumed dynamic sensors, five damaged beam segments are set, and each damage is given three levels of damage of 10%, 20% and 40% respectively. Then, based on the damage judgment effect of single damage and combined damage to these five beam segments, the indexes suitable for main girder damage identification are found out from various existing damage identification indexes used. Finally, CMSE is selected as the main method for damage monitoring of main girder of self-anchored suspension bridge because of its full damage identification ability and good noise resistance.