Bai, S. Gao, J. Geng, H. Wang, D. Wang, Y. Yu, C.H. Zhang, Y. Zhu, Y.S. JACoW Publishing Geneva, Switzerland 978-3-95450-216-5 10.18429/JACoW-eeFACT2018-WEXBA05 English 217-220 WEXBA05 detector photon solenoid scattering background Contribution to a conference proceedings 2019 2019-04 https://doi.org/10.18429/JACoW-eeFACT2018-WEXBA05 http://jacow.org/eefact2018/papers/wexba05.pdf The Circular Electron Positron Collider (CEPC) is a proposed Higgs factory with center of mass energy of 240 GeV to measure the properties of Higgs boson and test the standard model accurately. Machine Detector Interface (MDI) is the key research area in electron-positron colliders, especially in CEPC, it is one of the criteria to measure the accelerator and detector design performance. In this paper, we will introduce the CEPC superconducting magnets design, solenoid compensation, synchrotron radiation and mask design, detector background, collimator, mechanics assembly etc on, which are the most critical physics problem.