A ridge gap waveguide millimeter-wave crossover bridge structure device includes: an upper planar metal plate and a bottom planar metal plate arranged in parallel; a supporting structure fixedly arranged between the two planar metal plates; a ridge waveguide fixed on the upper surface of the bottom planar metal plate, with an air gap between the upper planar metal plate and the ridge waveguide; and a plurality of metal pins fixed on the upper surface of the bottom planar metal plate and evenly arranged around the ridge waveguide. The ridge waveguide includes two transmission lines arranged crosswise and four impedance transformation structures respectively connected to the ends of the two transmission lines. The distal end of each of the impedance transformation structures away from the connected transmission line is used to connect with external test equipment to be accommodated in four input ports in the bottom planar metal plate.