Jin, S. Dai, J. Gao, J. Gong, D.J. He, F.S. Li, Z.Q. Liu, Z.C. Sha, P. Zhai, J.Y. Zhang, P. Zhao, T.X. JACoW Geneva, Switzerland 978-3-95450-191-5 10.18429/JACoW-SRF2017-TUPB084 English 586-588 TUPB084 cavity ion controls cathode SRF Contribution to a conference proceedings 2018 2018-01 https://doi.org/10.18429/JACoW-SRF2017-TUPB084 http://jacow.org/srf2017/papers/tupb084.pdf Electropolishing (EP) System is a critical facility for SRF cavity treatment, especially for high performance cavities which are necessary for several great projects like LCLS-II, CEPC, Shanghai XFEL, and so on. So, an EP system was under development at IHEP. At this stage, we would like a horizontal EP facility. Main purpose is for elliptical SRF Nb cavities like 500MHz single cell cavities. Besides, it should be compatible for other frequency cavities, such as 650MHz and 1.3GHz cavities. In this paper, we will mainly report the preliminary design for the EP system. Several key points in the design will be also discussed.