Abstract: With the computer program TRANSOPTR including space charge effect calculations, a axial injection line for the CYCIAE-100 cyclotron is designed. The focusing structure is confirmed after considering space, focusing elements, vacuum, space charge effect, axial magnetic field and cost. The transfer matrix for the inflector under the real varying axial magnetic field is obtained by numerical tracking and it is built into TRANSOPTR for the beam line optics calculations from the downstream of the ion source to the exit of the inflector. The layout and the optical results of the injection line of CYCIAE-100, and the designs of the main elements in the injection line are given. After the electrode structure of the central region and the centering orbit are obtained, the beam matching is studied using the multi-particle tracing. The matching matrix is achieved by ellipses fitting for the tracking results and the analytic formula, which is useful in injection line design.