Terahertz time-domain spectroscopy(THz-TDS) is a new spectroscopic measurement technique based on ultra-fast femtosecond laser technology. THz-TDS technology has been applicated in material detection widely due to its good penetration and safety. In this paper, a method of indentifying transgenic soybean oil with THz-TDS technology was proposed. The methods of the Principle Component Analysis(PCA) and Support Vector Machine(SVM) were based on spectral analysis in the terahertz(THz) range. First, the absorbance spectrum was extracted from the original THz time-domain spectra data of the sample, and then imported into the model of PCA-SVM as an input source import. The utilization of the dimension-reduced data in PCA-SVM model can recognize the validation set accurately, and the transgenic soybeans can be accurately identified. The research results show that THz-TDS technology can identify the transgenic soybeans rapidly and nondestructively, and which could be widely applied in field of food safety inspection.