According to the ITER requirement, the availability of the poloidal field (PF) coil power supply system must be 98.3% during the life cycle of ITER. In order to meet this requirement, Reliability, Availability, Maintainability, and Inspectability (RAMI) analysis has been applied for analyzing the availability and reliability of the PF power supply system. First, the function analyses, which are described using the Integration Definition Function–language Ø or IDEFØ model are performed. Second, the failure mode effect and criticality analyses are used to calculate the risk level, present the potential causes and effects, and provide the risk mitigation actions to reduce the risk level for each failure. Third, the reliability block diagram is built to simulate the availability and reliability of the system. RAMI analysis provides a method that can be followed to improve the availability and reliability of the system, and from the results, the design requirement can be satisfied.