The invention provides a millimeter wave radial waveguide power combiner, comprising a peripheral metal wall, a coaxial connector, a glass insulator, an inner conductor probe and a capacitance loading structure, wherein the peripheral metal wall is provided with a through hole including an upper hole portion and a lower hole portion, the coaxial connector is connected with the through hole to serve as the input port of a radial waveguide, the glass insulator is arranged in the upper hole portion, an inner conductor penetrates through the through hole, the upper portion of the inner conductor probe and the lower hole portion form a coaxial waveguide, the lower portion of the inner conductor probe and the lower area of the peripheral metal wall form the radial waveguide, the inner conductor probe is perpendicular to the radial waveguide and positioned in the circle center of the radial waveguide which comprises a plurality of output ports, the capacitance loading structure is connected with the lower portion of the inner conductor probe, a ball is soldered to the probe and arranged at the lower portion of the inner conductor probe for bridging a gap between the capacitance loading structure and the inner conductor probe after melting by heating. The millimeter wave radial waveguide power combiner has the advantages of being good in power distribution consistency, easy to implement, low in cost and complexity, good in expandability and high in rate of finished products.