Wave energy is one of the most abundant renewable clean energy sources, and has been widely studied because of its advantages of continuity and low seasonal variation. However, its low capture efficiency and narrow capture frequency bandwidth are still technical bottlenecks that restrict the commercial application of wave energy converters (WECs). In recent years, using a nonlinear stiffness mechanism (NSM) for passive control has provided a new way to solve these technical bottlenecks. This literature review focuses on the research performed on the use of nonlinear mechanisms in wave energy device utilization, including the conceptual design of a mechanism, hydrodynamic models, dynamic characteristics, response mechanisms, and some examples of experimental verification. Finally, future research directions are discussed and recommended.