This paper pays direct attention to the path-tracking challenge of USVs with reduced actuation, proposing a novel Line-of-Sight (LOS) guidance law for estimating and compensating drift angle. The method aims to make the lateral error system converge and uses an Adaptive Iterative Learning Control (AILC) algorithm to optimize the uncertain drift angle parameter iteratively. Theoretical analysis demonstrates the convergence of control and lateral errors, ensuring the algorithm’s effectiveness. Simulation results indicate that the improved method can rapidly compensate for time-varying drift angles, exhibiting excellent path-tracking accuracy and robustness.