In order to reduce the loss of terahertz wave transmission, the loss characteristic of electromagnetic wave in corrugated waveguide has been studied. The calculation formula of attenuation constant for corrugated waveguide is obtained. Based on the numerical calculation, a low loss corrugated waveguide working at 220 GHz is designed, and the numerical results are verified by electromagnetic simulation. It is indicated that the theoretical result and simulation result agree well in HE11 mode.