To meet the high-speed and high-capacity demands of communication, a 300GHz electronic terahertz wireless transmission system is proposed, which incorporates Probability Shaping (PS), Discrete Multi-tone Modulation (DMT) and DFT-Spread (DFT-S) techniques. PS increases the Euclidean distance between constellation points, thereby enhancing the receiver sensitivity. In the system at most 55% bit error rate is decreased, enabling to extend transmission range. DFT-S technique reduces 1.68 dB peak-to-average power ratio of Orthogonal Frequency Division Multiplexing (OFDM) signals in the system, thus improving their resistance to nonlinear effects. In the 300GHz terahertz wireless transmission system, 12GBaud PS-16QAM OFDM-DMT signals and 10GBaud PS-64QAM DFT-S-OFDM-DMT signals were successfully implemented in 1m wireless transmission. Finally, the performance advantages of these digital signal processing techniques were compared.