The corrosion behavior of bulk amorphous Mg65Cu25Gd10 alloy was studied by electrochemical measurement. The potentiodynamic polarization tests were carried out in 0.01 mol/L NaCl solution and 0.1 mol/L NaOH solution with pH=13. The amorphous Mg65Cu25Gd10 alloy was spontaneously passivated at a significantly low passivation current density in the two kinds of solutions. The surface morphology and corrosive products of samples after dipping tests were characterized by scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS). The potentiostatically formed surface layers on Mg65Cu25Gd10 were investigated with a depth profile X-ray photoelectron spectroscopy (DP-XPS). The results show that the potentiostatically formed surface layer in NaOH solution is more compact and less porous than that in NaCl solution, indicating that the Mg65Cu25Gd10 alloy has a better corrosion resistance in the solution without Cl－.