Abstract: The electro-polishing parameters of high-speed electric railroad CuSn alloy contact wire were studied in this paper based on the principle of electro-polishing and anodic polarization curves.The optimum electro-polishing parameters of CuSn alloy contact wire were determined defined with improving of electro-polishing apparatus.The results show that as polished for 10~15min under 1.5~1.9V voltage at room temperature,the scratch of the sample could be removed and no defarmed layer is brought about so that the metallograph of the sample is more clear.