Ji, L.Y. An, S. Guan, F.P. Huang, P. Jia, X.L. Lv, Y.L. Wang, C. Wang, S.L. Zhang, T.J. Zheng, X. JACoW Publishing Geneva, Switzerland 978-3-95450-205-9 10.18429/JACoW-Cyclotrons2019-MOP007 English 39-41 MOP007 injection cyclotron ion-source MMI solenoid Contribution to a conference proceedings 2020 2020-06 https://doi.org/10.18429/JACoW-Cyclotrons2019-MOP007 http://jacow.org/cyclotrons2019/papers/mop007.pdf A 50 MeV cyclotron (CYCIAE-50) is been building at China Institute of Atomic Energy. CYCIAE-50 is a compact H⁻ cyclotron with the proton beam energy of 30 MeV to 50 MeV and the beam current of 10 uA. A multi-cusp H⁻ ion source with the beam current of 3 mA will be used for this machine. The design on the injection and central region of CYCIAE-50 has been finished. The way of matching the beam from ion source to central region and the design of central region will be present in this paper. In addition, some significant problems in central region will be discussed, including radial alignment, axial focusing, longitudinal focusing and energy gain, etc.