In order to solve the problem of communication between the ground and the aircraft, which is called “black barrier”, the vertically polarized terahertz wave is used to realize communication. Using the discharge device to generate plasma to simulate the plasma sheath on the surface of the aircraft, and an all-fiber coupled terahertz time-domain spectrometer is used to generate 0-1 THz waves. This paper studies the transmission characteristics of vertically polarized terahertz waves in uniform non-magnetized plasma with different electron densities from an experimental point of view. The experimental results show that the greater electron density, the faster propagation speed of the vertically polarized terahertz in the plasma; as the electron density increases, the attenuation becomes smaller. This research provides an important experimental reference for realizing the communication interconnection between the ground and the aircraft.