Sha, P. Dai, J. Dong, C. Feisi, H.F.S. Hao, J.K. Jin, S. Li, Z.Q. Liu, B.Q. Mi, Z.H. Wang, F. Zhai, J.Y. Zhang, X.Y. Zheng, H.J. JACoW Publishing Geneva, Switzerland 2226-0366 978-3-95450-194-6 10.18429/JACoW-LINAC2018-TUPO064 English 476-479 TUPO064 cavity SRF cryomodule collider electron Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-LINAC2018-TUPO064 http://jacow.org/linac2018/papers/tupo064.pdf CEPC will use 650 MHz cavities for the collider and 1.3 GHz cavities for the Booster. Each booster cryomod-ule contains eight 1.3 GHz 9-cell cavities, which is simi-lar as LCLS-II, E-XFEL and ILC. Each collider cryo-module contains six 650 MHz 2-cell cavities, which is totally new. Therefore, the pre-study mainly focuses on the 650 MHz 2-cell cavity. N-doping and vertical tests of 650 MHz 1-cell and 2-cell cavities have been carried out at IHEP, which have achieved good results. A test cryomodule, which consists of two 650 MHz 2-cell cavities, has also begun as the first step to the full-scale cryomodule.