Abstract: The vulnerability and short service life of optical modules directly lead to the communication reliability problems of secondary equipment in power grid. This problem can lead to sampling errors, protection device rejection, and even extended power outages. From the perspective of product life reliability, high temperature is the sensitive stress of optical module. The average failure time of a typical optical module is calculated by analyzing the Arrhenius model around the temperature. Based on the actual operation scenario of intelligent substation, the experimental scheme is designed considering the equipment spacing, environmental temperature and other factors. The sensitivity analysis is numerically expanded by the key factors of perturbation. The operating life of optical module is evaluated, and the rationalization suggestions for power grid operation and maintenance are given.