Regular maintenance and inspections can timely detect and eliminate defects of high-voltage cables

which is essential in reducing failure probability. However

a time-based maintenance without considering the difference in operational risk of individual circuit will lead to waste of resources. In order to ensure reliable and economical operation of cables

an optimization model for periodicity of inspections of HV cable based on risk assessment is proposed in this paper. According to the target of inspection

the cable circuit is divided into five parts: cable conduit

main body

joint

termination

and earthing system. And the index of failure criticality（IFC） model is used to calculate the frequency of failure of each cable circuit component. Then the time required to repair and the importance of the circuit are also considered

and all of them are applied in risk assessment. Moreover

the risk threshold requirements of cable system are taken into consideration. According to the different risk for each part of different circuits

the periodicity of inspection is optimized. Finally

after taking the HV cables from a certain area as an example

the above method is applied to effectively reduce the risk value of the cable circuit operation. The results show that the proposed method of determining failure frequency based on IFC model has the advantages that it does not depend on human intervention and does not need a large sample size to generate valid results. The optimization method for periodicity of inspections based on risk assessment can effectively reduce the risk of cable operation

and the cable system risk can be reduced by 70% after optimization.