The corrugated metal parallel plate waveguide composed by two parallel plates with subwavelength corrugations on both surfaces shows some similarities and differences with plasmon-assisted parallel plate waveguide are confirmed. A symmetrical corrugated metal parallel plate waveguide with gradually changed depth of corrugations is designed to convert electromagnetic wave between transmission mode and surface mode. Due to the field distribution and the power flow are concentrated on the corrugated surface at the intermediate region of the waveguide, a cylindrical perfect electric conductor put into the center of the waveguide does not affect its field distribution and transmission characteristics, namely the waveguide has stealth effect. The cutoff frequency of the upper sideband of corrugated metal parallel plate waveguide’s band gap changes linearly with the permittivity of sample substance which is filled in the corrugations, and therefore it can be used in dielectric sensing. The terahertz sensing characteristics are confirmed by the detection of samples such as diesel, liquid paraffin and olive oil. This work is helpful for exploring the application of the corrugated metal parallel plate waveguide in terahertz wave transmission, manipulation and terahertz device design.