<p>C45E4 steel, a medium-carbon structural steel widely used in high-stress industrial components, suffers from insufficient surface wear resistance under cyclic loads and sliding friction. To address this limitation, this study investigates the effect of non-contact ultrasonic-assisted laser cladding at different angles (25°, 35°, 45°, 55°) on the performance of Ni-WC coatings on C45E4 steel. Results show that ultrasonic cavitation and acoustic streaming synergistically promote heterogeneous nucleation, refine grains, enhance molten pool convection, and improve WC particle distribution uniformity. Among the tested angles, 55° yields optimal coating performance: the finest grain size with no columnar crystals at the base, a microhardness of 720.20 HV_0.025, 30.5% higher than the untreated group, and a 28.1% reduction in wear volume compared to the untreated group (S0). This work demonstrates that non-contact ultrasonic-assisted laser cladding at 55° effectively enhances the wear resistance of Ni-WC coatings on C45E4 steel, providing a practical solution for improving the service life of high-stress components.</p>