OBJECTIVE To explore the dynamic changes of main alkaloids in the processing process of Aconitum sinomontanum Nakai prepared by liquorice juice. METHODS Aconitum sinomontanum Nakai with or without liquorice juice were steaming for 0, 0.5, 1, 2, 3, 4, 5 h, respectively, and then dried. HPLC was used to determine the content of lappaconitine, ranaconitine and new components in different processed products of Aconitum sinomontanum Nakai. The simulated processing was carried out with the reference substance of lappaconitine and ranaconitine. The new components were separated by preparative liquid and analyzed by NMR and UPLC-QTOF-MS. RESULTS With the extension of steaming time, the content of lappaconitine and ranaconitine decreased significantly during the steaming Aconitum sinomontanum Nakai with or without liquorice juice, and two new peaks(peak 1 and peak 2) were produced and their content increased observably, this indicated that the new compounds were not related to licorice juice, only related to steaming process. Compared with the steaming process without liquorice juice, the contents of toxic and effective components lappaconitine and ranaconitine decreased moderately steamed with liquorice juice, indicating that the addition of liquorice juice steaming was more reasonable; The results of the simulated processing showed that the contents of lappaconitine and ranaconitine gradually decreased in the processing. After isolation and identification find the compound 1(peak 2) was 5-hydroxymethylfurfural. CONCLUSION The main alkaloids components of Aconitum sinomontanum Nakai are changed greatly after processing, which may be closely related to the “reduction of toxicity and increase of efficiency” in the steaming process of adding liquorice juice.