Copper-based coatings were prepared on the surface of Q235 steel by fiber laser under different powers. Microstructure, phase composition, corrosion resistance of the coatings were revealed by scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and electrochemical workstation, respectively. Results show that the coatings are well bonded to the substrate. The coating microstructure consists of cellular, coarse dendrites, fine dendrites and columnar grain structure from the bottom to the top. The coatings mainly contain two phases including Cu(Ni,Fe) and Ni(Cr,Mo,Fe) solid solution. The coating with two layers prepared under 2000 W exhibits optimal corrosion resistance due to its highest corrosion potential and lowest corrosion current density.