Abstract: With the large-scale application of cable in power system, the traditional cable periodic maintenance strategy is no longer reasonable due to its high cost and low efficiency. To solve the problems, combined with the rapid development of online monitoring technology in recent years, a new online evaluation strategy of cable operation status based on real-time operation data was proposed to achieve fast and accurate evaluation of cable operation conditions. Firstly,the temperature of cable middle joint,local discharge and sheath current were selected as the characteristic quantities reflecting the running state of cable to form the state characteristic quantity set.Secondly, based on cloud theory algorithm and combination weighting method, the improved cloud change matrix considering comprehensive weight was constructed by using real-time monitoring data and massive historical data of state feature sets. Furthermore, D-S evidence theory was adopted to calculate the membership degree corresponding to different operating states of cables, and finally realized the accurate online evaluation of cable operating states.Taking the actual monitoring data of a faulty power cable in Chuzhou, Anhui province as an example, the reliability and accuracy of the proposed strategy were verified by simulation(21 references cited).