A "cross-shaped" multi-hole terahertz waveguide directional coupler was designed. This compact structure has a large frequency band, stable coupling value and high directivity. The terahertz waveguide directional coupler structure was simulated and optimized with professional electromagnetic simulation software high-frequency structure simulator(HFSS) based on multi-hole coupling principle. The results show that the coupling degree of the terahertz waveguide directional coupler is 7.5±0.8 dB, the isolation is 30 dB, that is, the directivity is higher than 20 dB, and the return loss of each port is less than -20 dB in the range of 325 GHz to 475 GHz. Through high temperature and pressure simulation of the waveguide directional coupler, negative photoresist SU-8 is considered as a suitable material for structure fabrication. The directional coupler is fabricated by micro-electro-mechanical system(MEMS) technology, at the same time, sacrifice layer technology is applied to form the waveguide cavity structure. The uniformly-spaced coupling holes on the common wall of straight waveguide and coupling waveguide can be achieved by photolithography, therefore a wider bandwidth and a good coupling flatness of the directional coupler were obtained. This method improves the accuracy of the size and position of the coupling holes, reduces the reflection loss, and thus provides a new idea for the processing of terahertz waveguide structures.