The theory and simulation of the 0.5 THz waveguide dual-directional coupler is introduced. By using scheme of double rows, equal spacing, different diameters of multiple holes, the 0.325- 0.5 THz broadband waveguide dual-directional coupler is realized, and the simulation and test curves are given. It indicates that, the coupling factor is 7.6 dB±1 dB, the directivity is greater than 18 dB, and the return loss of the input port is greater than 16 dB. The coupler has excellent performance and has been applied to S-parameter test system.