Raft aquaculture is one of the popular farm modes for growing aquatic product in the ocean. However, tough conditions in the open ocean often impose severe damages on the raft systems. Therefore, comprehensive studies on the mechanics of the raft systems exposed to waves will greatly give help to optimizing raft system design and construction. This paper focuses on the mechanics of a typical long-line raft lug aquaculture system under wave conditions. In this paper, the numerical simulation was used for this study. The raft system was assumed as a flexible structure which was composed of nodes connected with springs. Wave forces on the rope and floating balls were calculated using Morison equations. Second order differential equations were established based on Newton's second law. The equations were resolved using fourth-order Runge-kutta method to find out the inner tension force and displacement of each element. It was found that free-weight and system angle have an effect on long-line rope aquaculture facility. Long-line displacement is negatively related with free-weight. The displacement of long-line decreased as free-weight increased.The force of long-line, back anchor rope, float ball rope and lifting rope increased as free-weight increased. But the force of front anchor rope decreased as free-weight increased. Float ball pattern had little impact on the system's movement and force. Anchor rope force and the displacement of long-line had positively correlated relationship with system angle at 0° to 60°. They increased as the angle increased. Anchor rope force and the displacement of long-line had negative correlated relationship with angle at 60° to 90°. They decreased as the system angle increased. The force of long-line, float ball rope, the lifting rope affected by the system angle is small. The results have important significance on evaluating the safety of the raft culture system. Deep-water long-line rope aquaculture facility belongs to the typical flexible multi degree of freedom offshore structures, and this research results can provide the reference for designing deep-water long-line rope aquaculture facility and safety evaluation. But the hydrodynamic characteristics of the deep-water long-line rope aquaculture facility are related to its structure and environmental factors, therefore we need specific conditions and specific analysis in the raft system designing and safety assessment.