Abstract: OBJECTIVE Based on near infrared spectroscopy(NIR) spectroscopy technology, taking alibiflorin, paeoniflorin, density and soluble solid content as quality control indicators, to carry out rapid detection of Moluodan aqueous extract in the concentration process, so as to realize the on-line quality control of Moluodan concentration process.METHODS Collect the on-line NIR spectrum of Moluodan aqueous extract in the concentration process, and collect samples. Based on HPLC, drying method and other physical and chemical instrument analysis methods, the content of important indexes of Moluodan aqueous extract were determined. Then the NIR spectrum correction model of important indexes was established by using partial least square method. Finally, the performance of the correction model was verified, and the correction model was used to predict the changes of important indexes in the concentration process of Moluodan aqueous extract.RESULTS The correlation coefficients(R) of the established calibration models for alibiflorin, paeoniflorin, density and solid content were > 0.98, the R of the validation set was > 0.99, and the relative deviation of the validation set was < 7%.CONCLUSION NIR spectral analysis technology can realize the rapid detection of alibiflorin, paeoniflorin, density and solid content in the concentration process of Moluodan aqueous extract, and the results are accurate and reliable.