The space crafts, such as spaceship, space shuttle and so on, will face a famous "blackout" problem when they re-enter the earth's atmosphere at high velocity. The plasma sheath severely affects the propagation of the incident electromagnetic wave and causes severe electromagnetic wave attenuation, which results in the communication failures between the space crafts and the ground control center. It is important to study the properties of terahertz wave propagation in non-magnetized plasma, for using the terahertz wave communication is an alternative method to solve the reentry blackout problem. The terahertz wave propagation characteristics in non-magnetized plasma are studied in this paper. The variations of the terahertz wave propagation properties with the terahertz wave frequency, plasma density, plasma collision frequency and the thickness of the plasma are acquired. Some new phenomena are found i.e., there appears periodic oscillation on the reflectivity curve with the increase of terahertz wave frequency, and the period of oscillation is 0.03THz. The oscillation amplitude increases with the increase of terahertz frequency, decreases with the increase of plasma density, and increases with the increase of plasma collision frequency. The oscillation is attributed to the multiple reflections of the electromagnetic wave at the interfaces at z = 0 and z = -d. The terahertz wave propagation properties in plasma are studied experimentally with the shock tube, and the experimental results match well with the theoretical ones. Both the theoretical and experimental results indicate that using terahertz wave communication is an effective way to solve the reentry blackout problem.%本文对太赫兹波在非磁化等离子体中的传输特性进行了理论和实验研究，得到了非磁化等离子体中太赫兹波传输特性随太赫兹波频率、等离子体密度、碰撞频率和厚度的变化规律．发现了一些新的现象：随着太赫兹波频率增加，反射率曲线出现周期性振荡，振荡周期为0．03THz．随着太赫兹波频率增加，振荡幅度增加：随着等离子体密度增加，振荡幅度减小；随着等离子体碰撞频率增加，振荡幅度增加．反射率曲线出现振荡的原因是电磁波在z=0和z=-d界面处的多次反射所致．以激波管为实验平台进行了0．22THz太赫兹波在等离子体中传输特性的实验研究，实验结果和理论结果符合较好．理论和实验结果均表明，采用太赫兹来实现地面与飞行器之间的通信互联是解决黑障问题的可选途径之一．
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