Abstract: A novel Tomlinson-Harashima precoding (THP) transmission method in MIMO-OFDM system was presented, applying lattice reduction auxiliary (LRA) and TH pre-coding in the transmitter and LRA and serial interference detection algorithm in the receiver. This novel transmission method can transfer channel matrix into an approximate orthogonal matrix to significantly improve the anti-noise performance. Simulation and analysis results show that LRA-THP transmission can increase the system performance by 1~2 dB under error rate of 10<sup<-2</sup< comparing with traditional THP transmission, and LRA-QRM-SIC detection algorithm can provide better performance than LRA-MMSE algorithm by 1 dB.