This paper presents the analyzed results of both dynamic simulations and steady-state performance of a tidal power generation system (TPGS) containing a permanent-magnet synchronous generator (PMSG) driven by a tidal turbine through a gearbox. The stator windings of the tidal PMSG are connected to an onshore distribution system through an ac-to-dc converter, a dc-to-ac inverter, a step-up transformer, and a transmission cable. A d-q axis equivalent-circuit model is employed to establish complete dynamic equations of the studied system under three-phase balanced loading conditions. A frequency-domain approach based on eigenvalue analysis and a time-domain scheme based on nonlinear-model simulations are both carried out to systematically determine the dynamic stability of the studied system under different operating conditions. It can be concluded from the simulation results that the studied TPGS subject to different disturbance conditions can maintain stable operation.