The properties of Terahertz (THz) waves propagation in a bounded plasma slab with high plasma density and high collision frequency are studied in this paper. The method of impedance transformation in multiple dielectrics is used to describe the propagation of THz waves in the plasma layer. The effect of various plasma parameters such as the plasma density, sheet thickness, incident wave frequency and collision frequency on the power transmission, absorption and reflection is investigated. The calculated numerical results show that a THz wave can transmit though a dense and high collision frequency (to the order of 1012~THz) plasma with reflection less and absorption less power. When the change of plasma density leads the plasma frequency to be in the vicinity of the incident THz wave frequency, the plasma can absorb the most THz wave power. The potential applications of these propagation properties are discussed in this paper.