In order to control the content of trans fatty acids (TFAs) in the process of oil deodorization, this paper presents a fast method for detecting trans fatty acids (TFAs) content in soybean oil based on near-infrared spectroscopy. First, we prepared 100 soybean oil samples with different TFAs content, and detected precisely the values of TFAs contents by gas chromatography. Then, the near-infrared spectrum of oil samples was scanned and denoised by various methods, and it is found that the denoising effect of MSC was the best. In order to study the characteristic absorption of TFAs in near-infrared region, we used a variety of iPLS methods to select the characteristic band of the spectral data, and the characteristic absorption band of TFAs is selected as 7 258～7 443/6 502～6 691/6 120～6 309 cm-1. On this basis, the Kalman filtering algorithm is used to select the characteristic wavelength variables, and 27 TFAs characteristic wavelength variables are optimized. The deep belief network (DBN) is adopted to construct the correction model, and we found that the performance of the DBN model is the best adopting 3 hidden layers and 50-35-90 hidden layer nodes. Finally, the DBN model with this parameter is compared with the regression model of trans fatty acid content established by PLS. The results show that: when we used the whole denoised spectrum to construct model, the prediction effect of DBN is better than that of PLS, R2 is 0.879 4, RMSEP is 0.060 3 and RSD is 2.18%. When we used the selected characteristic band to model, the prediction effect of the PLS model is better than that of the DBN model. Using the 27 optimized characteristic wavelength variables to construct model, DBN has a good prediction effect, R2 is 0.958 4, RMSEP is 0.035 0 and RSD is 1.31%. It shows that the generalization ability of DBN is better, which achieved better prediction results by using a small number of wavelength variables. The proposed method in this paper can meet the practical needs, and provide technical support for online detecting and regulating TFAs content and producing low/zero TFAs oil products.