The reliability of power communication network plays an important role in the safe operation of smart grid. The reliability model of the typical electric power communication system is established by using the hierarchical modeling. First， the power communication system is decomposed into terminal layer， access layer， sub-station communication layer and master station control layer subsystem by means of top-down decomposition method. Then， the reliability of basic products is evaluated by using parameters such as mean time between failures， mean time without failures and mean time to repair， and the reliability of each subsystem is evaluated by using non-redundant system， fully redundant system， partially redundant system and collateral system. Finally， the bottom-up synthesis method is used to evaluate the reliability of the whole network according to the topology of the system. The reliability analysis method proposed provides a theoretical method for the reliability evaluation in power communication network.