Expansion joints in long-span bridges play an important role in the safety of the bridge,and they are most vulnerable to damage and rather difficult to repair.Based on the analysis of the measured data by Health Monitoring System of Jiangyin Bridge,Runyang and Sutong Bridge,the method of analysis and assessment of large-displacement expansion joints of long-span cable-supported bridges was established.After the introduction of relationship between measured data and the state of expansion joints,it was pointed out that characteristics of longitudinal displacement of suspension bridges and cable-stayed ones were different,which had significant impact on expansion joints.Based on the above,specific measures to improve performance and service life of large-displacement expansion joints were proposed,which was supposed to guide in in some way the assessment of similar large-displacement expansion joints.