This study employs a phase-field–lattice Boltzmann coupled model to investigate the effect of forced convection on the lamellar eutectic growth of Al-Cu alloys. Results indicate that forced convection tilts lamellar structures toward the flow direction, enhances solute diffusion, and causes solute concentration to deviate asymmetrically from the solid phase centerline. Greater convection intensity leads to more pronounced interface asymmetry. Increased undercooling weakens convective effects and reduces tilt angles, while larger lamellar widths diminish convective influence and yield smaller tilt angles. The study reveals a synergistic regulatory mechanism between these factors. Simulations indicate that without convection, layers grow vertically with solute symmetrically distributed along the solid centerline. Interlayer lateral diffusion promotes synergistic α-β phase growth. Forced convection (along the x⁺ direction) enhances solute transport in the flow direction while weakening counter-current transport. This shifts the triple point and creates asymmetric solute distribution—e.g., higher α phase concentration to the left of the centerline—causing layer tilting. Increasing convection intensity (expressed as A/A₀, where A₀ corresponds to the coefficient for a 0.5° tilted layer) exacerbates asymmetry at the solid-liquid interface and reduces the distance between the interface peak and the triple point. Higher undercooling (0.8-1.4 K) enhances growth driving force and reduces solute trapping capacity, weakening convective effects and decreasing the tilt angle. When undercooling is minimal and convection is strong, the tilt angle significantly increases. As the interlayer spacing (6.4-19.2 μm) increases, solute exchange at the interface becomes more frequent, convective interference weakens, and the tilt angle decreases; under conditions of small spacing and strong convection, solutes are easily washed away, inhibiting lamellar growth. In summary, forced convection directly alters the morphology of the solute transport control layer. Supercooling and interlayer width indirectly modulate convective effects by influencing growth driving forces and interfacial solute exchange. These three factors synergistically regulate eutectic growth, providing a theoretical basis for controlling eutectic microstructure.