In this article， the elliptic waveguide TE₀₁-TE₁₁ mode converter is studied. The proper elliptical waveguide cross section is selected， the phase re-matching method is used in the elliptical waveguide longitudinal contour line function， and the longitudinal contour line optimization is performed using a particle swarm algorithm， and the designed elliptical TE₀₁-TEs₁₁ mode converter has a conversion efficiency of 99.16% at 28 GHz. The efficiency of the mode converter at 27-29.3 GHz is more than 90%， and the relative bandwidth is 8.2%. The conversion section of the designed TE₀₁-TEs₁₁ elliptic mode converter is half of the existing length. The designed elliptical mode converter is connected to two transition segments and simulated and verified in CST， and the results are consistent with the theoretical calculations. An efficient， compact， high-power elliptical waveguide TE₀₁-TE₁₁ mode converter with a center frequency point of 28 GHz is designed.