Objective To investigate the effects of plasma spray power and time on the phase, microstructure and corrosion-resistance of the amorphous coating on the boiler tubes. Methods XRD, SEM and electrochemical polarization research were adopted. Results The coating with high fraction of amorphous phase was obtained, which had a flat and compact surface. The amorphous fraction and porosity decreased and the density increased with the increasing spray power and time. The coatings exhibited an excellent ability to resist corrosion with wide passive region in 0. 5 mol/ L H2SO4 and 3. 5% NaCl solutions. And the coatings exhibited wider passive region and lower corrosion current density in 0. 5 mol/ L H2SO4 and 3. 5% NaCl solutions, respectively. With increase of the spray power and time, the anodic polarization curves of the amorphous coatings were passivated with wider passive region and lower passive current density. Conclusion The path and flow resistance that corrosive liquid permeated the substrate were increased, and the corrosion resistance of the coating was improved, owing to the decreased porosity and increased coating thickness with the increasing spray power and time.