Abstract: The reliability of a warm standby repairable system, composed ofnidentically distributed components and repair equipment, is discussed. Under the conditions that the lifetime and repaired time of the components and the switch in the system are subject to exponential distributions and all variables are mutually independent, two models are set up respectively for two situations that the systemfails immediately or notwhen the switch fails. Fromthe homogeneousMarkov process, the transition probability of the system is determined. And the reliability of its mean lifetime and the first failure time forn=2 are obtained. Finally, the results obtained from the two models accord with the present ones under some special conditions.