<p>A three-dimensional numerical model of sand wave dynamics, incorporating the interaction of currents and waves at various angles, has been developed using the Regional Ocean Modeling System (ROMS). This model accounts for both bedload and suspended load sediment transport under combined waves and current conditions. The investigation examines the influence of several key parameters, including the rotation angle of sand waves relative to the main current, tidal current velocity amplitude, residual current, water depth, wave height, wave period, and wave direction, on sand wave evolution. The growth rate and migration rate of sand waves decrease as their rotation angle increases. For rotation angles smaller than 15°, sand wave evolution can be effectively simulated by a vertical 2D model with an error within 10%. The numerical results demonstrate that variations in tidal current velocity amplitude or residual current affect both vertical growth and horizontal migration of sand waves. As tidal current velocity amplitude and residual current increase, the growth rate initially rises to a maximum before decreasing. The migration rate shows a consistent increase with increasing tidal current amplitude and residual current. Under combined waves and current, both growth and migration rates decrease as water depth increases. With increasing wave height and period, the growth rate and migration rate initially rise to maximum values before declining, while showing a consistent increase with wave height and period. The change rate of sand waves reaches its maximum when wave propagation aligns parallel to tidal currents, and reaches its minimum when wave propagation is perpendicular to the currents. This phenomenon can be explained by the fluctuation of total bed shear stress relative to the angle of interaction between waves and current.</p>