The time-varying aging failure rate（AFR） can simulate the failure characteristic of protection devices more accurately than the mean failure rate（MFR）. This paper focuses on the time-varying failure rate（TFR） characteristics for the HVDC protection devices and firstly divides the failure data into two catalogs， i.e. the aging failure and random failure. Next， with the above data， the time-varying aging failure rate（AFR） is estimated with the Weibull distribution function， and the constant random failure rate（RFR） is drown up with estimating exponential distribution function; then TFR is obtained with the addition of AFR and RFR. Furthermore， based on the field failure data of a regional power grid， TFR of the grid can be obtained and the differences in time-varying failure characteristic of different batches and modules of protection devices are given. Results show that different batches of the devices are， respectively， in the loss failure period and the random failure period， thus the maintenance strategy should be formulated severally. Meanwhile， results also indicate that power and communication unit is easy to enter the loss failure period.