A single-layer dielectric matrix transmission model was developed to study the transmission characteristics of terahertz waves in high temperature plasma. The variation in the terahertz wave under the influences of plasma electron density, thickness, applied magnetic field strength, and temperature was studied. The numerical analysis results indicate that under different conditions, the high-temperature plasma exhibits different transmission characteristics for the incident wave. The reflectivity increases and transmittance decreases with increasing plasma-electron density and thickness; then, a magnetic field can be used to improve the attenuation. Therefore, the thickness decreases with decreasing electron density of the plasma, and the influence of the increasing temperature on electromagnetic waves decreases. Adjusting the magnitude of the applied magnetic field and avoiding the attenuation peak can prevent communication blackouts.