The design goals of the central region for the230 MeV compact superconducting synchrocyclotron can be briefly summarized in four aspects:1)the phase acceptance is maximized;2)the electric field provides axial focusing to compensate the weak focus of magnetic focusing;3)the The design goals of the central region for the 230 MeV compact superconducting synchrocyclotron can be briefly summarized in four aspects: 1) the phase acceptance is maximized; 2) the electric field provides axial focusing to compensate the weak focus of magnetic focusing; 3) the