In this paper, we present the study of system dynamics of the floating kuroshio turbine (FKT) system which is designed to harness ocean current energy. We focus on the mooring line system design and its interaction with the FKT system. The effects of line diameter and two different auxiliary line systems were studied. Their responses in waves were also investigated. We integrated several commercial and in-house packages. The system buoyancy and weight and their centers were estimated using the Rhino software. The system hydrodynamic coefficients were obtained through WAMIT, system drag coefficient through FLUENT, turbine propulsive force through lifting surface code, and system dynamics through OrcaFlex. The results show that the mooring line system can create strong influence on the FKT system operations in the ocean current environments.