Because of the poor wear resistance and low hardness of magnesium alloys, the modification of their surface using laser remelting technology is particularly beneficial, especially, the influence of the laser power factor is important. To investigate the influence of the power factor in laser remelting on the microstructure, hardness, and friction and wear properties of rare-earth magnesium alloys, the laser remelting experiments with Mg-1.85Y-7.91Zn-0.75Zr (mass fraction,%) alloy were conducted under different laser powers using a 3 kW DILAS semiconductor laser. The structure, morphology, phase composition, and distribution of the samples were observed by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive spectroscopy (EDS). Microhardness tests were conducted to measure the Vickers hardness and elucidate the effects of different laser powers on the structure and mechanical properties of the alloy. The results show that the macrostructure of the alloy after the remelting process becomes finer and with increasing laser power, the grain increases and the second phase becomes more dispersed. Hardness and wear resistance are enhanced because of fine-grained strengthening, solid solution strengthening, and dispersion strengthening. Among the changes, under laser powers of 800, 1000, 1200, and 2000 W, the average Vickers hardness values of the remelted fine crystal region are 90.97, 93.47, 94.20, and 95.53, respectively, whereas the average Vickers hardness value of the coarse crystal base material is only 63.90. When the alloy is laser-remelted under a power of 2000 W, it exhibits a hardness 49.50% greater than that of the base material. As the power is increased, the wear resistance is enhanced and the wear gradually transitions from adhesive to abrasive wear. The laser remelting technology substantially strengthens the rare-earth magnesium alloy, and increasing the laser power can dramatically increase the hardness, antifriction, and antiwear properties of the alloy.