Based on the curved circular waveguide coupling theory and regular circular waveguide junction mode matching method, the TE01-HE11 Mode Converter model was designed using the optimization parameter of the waveguide mode conversion structure obtained from relevant numerical calculation program, and was successfully simulated and verified by the CST software. The system is mainly composed of three parts: a TE01-TE01 mode transition, two circular waveguide mode converters for TE01-TE11 and TE11-HE11. The calculations showed that the conversion efficiency of the TE01-HE11 mode converter system is over 99% within the bandwidth of 5% relative to 24.13 GHz. The results of simulations and test are consistent with that of calculation.