Guo, J.J. Gu, Q. Hou, H.T. Tan, J.H. Zhang, M. JACoW Publishing Geneva, Switzerland 978-3-95450-184-7 10.18429/JACoW-IPAC2018-THPAL101 English 3872-3874 THPAL101 Contribution to a conference proceedings 2018 2018-06 https://doi.org/10.18429/JACoW-IPAC2018-THPAL101 http://jacow.org/ipac2018/papers/thpal101.pdf Shanghai Coherent Light Facility (SCLF), a superconducting accelerated structure-baesd FEL device, is now under development at Shanghai Institute of Applied Physics, Chinese Academy of Sciences. We investigate effects of cryogenic losses caused by trapped longitudinal high order modes (HOM). Results of calculations are presented for losses caused by HOMs excitation in the acceleration RF system of the continues-wave (CW) linac of SCLF.