Wide are monitoring, protection and control (WAMPAC) plays a critical role in smart grid development. Since WAMPAC frequently has the tasks of executing control and protection actions necessary for secure operation of power systems, its reliability is essential. This paper proposes a novel approach to the reliability analysis of WAMPAC systems. WAMPAC system functions are first divided into four subsystems: the measured inputs, the communication, the actuator and the analytic execution subsystems. The reliability indices of the subsystems are computed then using Monte Carlo approach. A sensitivity analysis is also described to illustrate the influence of different components on the system reliability.