Abstract: In a transient signal system, the TX/RX coupled interference is one of principle interferences and has great influence to the system capability, especially to the near field remote sensing system such as Surface Penetrating Radar(SPR). Suppression of the coupled interference is very important for the system performance. With consideration of the sys-tem operating condition, the signal and system character, realization object of the signal processing ,thc Principal Component Analysis (PCA) method is employed. The validity of the method for the engineering application is demonstrated with theoretical analysis and experiments in this paper, and it can bo applied to real-time processing.