Abstract: As a form of ocean energy, tidal energy is extremely abundant in oceans, with the characteristics of being clean, reliable, predictable and renewable. In the development of tidal energy, a bi-directional tubular turbine has been widely adopted for power generation. The tubular turbine converts the energy extracted from tides into mechanical energy, and further into useful electricity. The tubular turbine has been well designed suitable for generating power from both flow directions, in order to take full use of the tidal energy not only in the flood tide state but also during the ebb tide state. However, the operation condition of the tubular turbine will be definitely affected by the movement of the wave caused by tide, especially for the reverse power generation direction in which the flow direction is from the ocean to the turbine installed in the hydraulic dam. In this case, under the influence of ocean wave current conditions, the change of hydrodynamic performance during the reverse operation of tidal energy units is an important issue to be considered during the development of tidal energy units. In this paper, the nonlinear second-order Stokes wave law was used to simulate the ocean tide flow, and the second-order Stokes wave formula ocean wave flow condition model has been established based on actual oceanic flow conditions. The chosen tubular turbine had 4 runner blades, with a hub ratio of 0.38 and a runner diameter of 2.5 m. The turbine consisted of an intake part with body, guide vanes, runner and straight draft tube. In order to discrete the computational domains, the grid generation tool ICEM CFD was used to generate high quality structure grids. The number of grids chosen for simulations was approximately 6.5 million, after a grid-independent study with the hydraulic efficiency of the turbine being the examined criterion. The RNG k-. turbulence model was chosen to close the time-averaged N-S equations. Transient simulations with considering the effect of the ocean wave on the flow have been realized with the help of ANSYS CFX, with a VOF (volume of fluid) model being adopted in the ocean domain to simulate the free surface of the boundary between the liquid and air. Based on the numerical results, the internal flow characteristics of a tidal energy turbine tune turbine in reverse running under dynamic wave flow boundary conditions were studied. In addition, the influence mechanism of tidal wave on the stability of the tubular turbine operation was discussed in detail. The results showed that: 1) Considering the coupling of wave and flow, most of the kinetic energy was lost after the tidal wave collided with the dam, and the reflected wave flow was therefore formed, which covered the air before the next peak of the wave and produces bubbles entering into the interior of the ocean. 2) The interaction between the incoming tidal wave and the reflected tidal wave on the wall of the dam was the cause of the vortex at the water intake of the tidal tubular turbine. The formed vortex was rotated under the liquid surface and flows into the internal flow field. The upper side of the flow path compressed the flow area to form a low-pressure and low-speed vortex region, which changed the flow distribution of the internal flow field and the characteristics of the tubular turbine. 3) The action of the dynamic wave caused the force on the rotor blades of the tidal tubular turbine to fluctuate greatly, and the low-frequency amplitude of the blade force increases with the development of the air-entraining vortex. At the same time, the fluctuation of unit output under the influence of wave current reached 3.86%, which was much higher than that of less than 1% under no-wave condition, resulting in a decline in power quality.