A method based on on-line enrichment technique and diffuse reflection near infrared spectroscopy(DRNIRS) was developed to detect rapidly trace plasticizer diisooctylphthalate(DEHP) in drink.DEHP solutions were passed through and concentrated with the polyethersulfone(PES) membrane and then the surface of the membrane was detected directly to collect diffuse reflection NIR(DRNIR) spectra.The wavenumber regions of 4 420-4 060,4 700-4 540,6 040-5 600 cm-1 were selected to build calibration models according to the transmission NIR spectrum of DEHP.The original spectral data were pretreated by multiplicative scattering correction(MSC),first derivative,second derivative,multiplicative scattering correction combined with first derivative and multiplicative scattering correction combined with second derivative，respectively.Meanwhile，partial least squares(PLS) calibration models with leave-one-out cross validation were established，and samples in the prediction dataset were predicted by the calibration models.The results demonstrated that the predictive results of the PLS calibration models were the best when the spectral data were pretreated by first derivative，and the latent variable number was 7.The root mean squared error of calibration(RMSEC) for the calibration samples was 0.188 7 mg/L，and the root mean squared error of prediction(RMSEP) for the prediction samples was 0.232 4 mg/L with mean relative error(MRE) of 6.29% in the DEHP mass concentration range of 0.5-5.0 mg/L.