The reliability of power quality monitoring device will affect the orderly development of on-linemonitoring and evaluating work. However

with the long term operation of power quality monitoring devicein the complicated environment condition

the aging of its elements will probably lead to reliability reduc-tion and thus affect the correctness of the on line monitoring data. Therefore

it is necessary to analyze andevaluate the reliability of the power quality monitoring device. In this paper

a kind of reliability analysismethod for the power quality monitoring device based on nonparametric estimation is proposed

which canachieve remote analysis on the operation status of the monitoring device

find the hidden trouble of the reli-ability of the monitoring device so to provide technical support for the power quality management level.Both the validity and applicability of the method are verified by the calculation example.