Soybean oil is often contaminated by aflatoxin B (AFB) which is regarded as a class I carcinogen. The feasibility of rapid determination of AFB in soybean oil with terahertz spectroscopy was examined. t-SNE, as the pre-treatment method was used to get the best features and combined with different chemometrics including least squares-support vector machines (LS-SVM), back propagation neural network (BPNN), random forest (RF) and partial least squares (PLS) to find the best determination model. The excellent prediction results could be obtained using BPNN combined with t-SNE with correlation the coefficient of prediction (R) was 0.9948 and the root-mean-square error of prediction (RMSEP) was 0.7124 µg/kg. Besides, THz spectroscopy was proved to be feasible to detect AFB at 1 µg/kg in soybean oil (over 90% accuracy). It was concluded that THz spectroscopy together with chemometrics would be a promising technique for rapid determination of the AFB concentration in soybean oil.