For fault detection in the distribution network of Smart Grid and isolate the faulty load switches with in the limited period, FDIR algorithm runs on DFA controller which are installed at the Communication network of Smart Grid in order to control the power devices of distribution network. For its reliability analysis, formal verification is necessary in order to investigate its accuracy, stability and efficiency when fault is occurred on the network. Through probabilistic analysis of FDIR based distribution network via PRISM model checker tool, we can estimate the failure probability of network and take a corrective action and maintenance so that, faulty component can be replaced in advance to avoid the complete failure of system.