The inter-related parameters of higher order transverse magnetic (TM) modes in coaxial cavity are calculated and analyzed. It is found that TMn10 modes have large mode intervals. There exists a maximum characteristic impedance while keeping the specific cavity outer radius constant. Large cross-section cavity can be employed in higher frequency range. The solutions show good agreement with the results simulated by ISFEL 3-demention and HFSS, softwares used for electromagnetic simulation. The results calculated can serve as a database from which the optimum seeking in design can be gotten instantly instead of the time-consuming simulation by trial and error.