The inter-related parameters of higher-order TM mode was investigated of microwave cylindrical coaxial cavities. Using FORTRAN program, parameters of the cavity were obtained, such as cavities' size, orders of TM mode, frequencies, radii of positions of longitudinal maximum electric field intensity and characteristic impedances in the cavities etc. The calculated result was in good agreement with that simulated by ISFEL 3D. Database used for optimum seeking can be gotten instantly this way instead of the time-consuming emulation by trial and error method.