Abstract: This paper considers a one unit repairable systems with single repairman vacation. If the system fails the repair starts immediately unless the repairman is in vacation time, in which case a waiting repairable time is needed. So that the system may be in one of three states: the working state, the waiting repair state and the being repaired state. By using the total probability decomposition and the tool of the Laplace transform, the following reliability problems are discussed: 1) the reliability, pointwise availability and the stead-state availability; 2) the expected failure number during a given (O,t] and the stead-state failure frequency. Some important reliability results such as the pointwise availability and stead-state availability are obtained.