Abstract: In order to understand the corrosion resistance of different materials surfaces machined by micro wire electrical discharge machining(MWEDM), the specimens of three kinds of materials, including W18Cr4 V, 60Si2Mn and M42, were separately processed. The micro electrolytic cell equipment and electrochemical workstation were applied to test the corrosion resistance of specimen surfaces, and the electrochemical impedance spectroscopy and potentiodynamic polarization curves were measured and analyzed. Besides, the surfaces after corrosion were observed with inverted metallurgic microscope, and were compared to flat grinding surfaces. The results showed that corrosion resistance of MWEDM surfaces was superior to that of flat grinding surfaces. For different materials, corrosion resistance of MWEDM surfaces was significantly different from each other. For the same material, the surface with better corrosion resistance could be obtained by using appropriate processing parameters.