Recently, several research studies are being conducted on Ocean Wave Energy Conversion (OWEC) systems that convert wave motion into electricity. The efficiency of OWEC systems is a parameter of great significance. Thus, it is important to consider factors that affect the efficiency of the system, such as ocean wave properties, airflow characteristics of the OWEC systems, and manufacturing inaccuracies. However, these parameters have inherent uncertainties, which should not be disregarded. Without considering these uncertainties, the feasibility assessment of an OWEC system can be misleading. For this study, the following research question was developed: can probabilistic analysis be used to determine the reliability of the efficiency of the OWEC system? To answer this research question, the specific aims developed were: (1) to quantify the uncertainties of the input parameters, and (2) to determine the reliability of efficiency of the OWEC system. The reliability of the efficiency of the system was calculated probabilistically. Probabilistic sensitivity analysis was performed to determine the random variable that had the most impact on the reliability of the efficiency of the OWEC system. Advanced Mean Value (AMV) method was used to determine the probability of failure. NESSUS software was used to perform the probabilistic analysis. In order to assess the reliability of the system, a target efficiency was set and the probability of achieving this efficiency under uncertain input conditions was investigated. The deterministic and probabilistic results were also compared. The results showed that, probabilistic analysis approach can reveal the reliability of the system efficiency by accounting for the wave parameter and manufacturing uncertainties. Moreover, sensitivity analysis showed the variables that had the most impact on reliability of efficiency.