ObjectiveTo investigate the transformation mechanism and content variation of saponins from Polygalae Radix before and after being boiled with licorice juice and water. MethodSimulated licorice juice boiled products and simulated water boiled products of onjisaponin B， onjisaponin Z， onjisaponin F， polygalasaponin ⅩⅩⅧ were prepared by simulated processing technology， and analyzed by ultra-performance liquid chromatography-quadrupole-electrostatic field orbitrap high resolution mass spectrometry（UPLC-Q-Exactive Orbitrap/MS）. Then the contents of onjisaponin B， onjisaponin Z， onjisaponin F， polygalasaponin ⅩⅩⅧ and tenuifolin in Polygalae Radix， licorice-boiled Polygalae Radix and water-boiled Polygalae Radix were determined by UPLC-triple quadrupole tandem mass spectrometry（UPLC-QQQ-MS/MS）. ResultDuring the boiling process with licorice juice and water， onjisaponin B could be hydrolyzed to produce 4-methoxycinnamic acid， desacylsenegin Ⅲ， polygalasaponin ⅩⅩⅧ and tenuifolin， onjisaponin Z could be hydrolyzed to produce 3，4，5-trimethoxycinnamic acid， onjisaponin TF， polygalasaponin ⅩⅩⅧ and tenuifolin， onjisaponin F could be hydrolyzed to produce 3，4，5-trimethoxycinnamic acid， onjisaponin G， polygalasaponin ⅩⅩⅧ and tenuifolin， and polygalasaponin ⅩⅩⅧ was hydrolyzed to produce tenuifolin. After being boiled with licorice juice or water， the content of onjisaponin B decreased significantly（P<0.05， P<0.01）， but the contents of onjisaponin Z， onjisaponin F， polygalasaponin ⅩⅩⅧ and tenuifolin increased significantly（P<0.05， P<0.01） in Polygalae Radix. Compared with the water-boiled products， the contents of onjisaponin Z and tenuifolin increased significantly（P<0.05， P<0.01）， and the change of tenuifolin content was the most significant in the licorice-boiled products.However， there was no significant difference in the content of onjisaponin B， onjisaponin F and polygalasaponin ⅩⅩⅧ between the water-boiled products and the licorice-boiled products. ConclusionBeing boiled with licorice juice or water can hydrolyze onjisaponin B， onjisaponin Z， onjisaponin F and polygalasaponin ⅩⅩⅧ， and generate secondary glycosides and aglycones（organic acids） through deglycosylation， which leads to obvious changes in the contents of onjisaponins after Polygalae Radix being processed.It is inferred that licorice juice can promote the hydrolysis of some onjisaponins in Polygalae Radix to onjisaponin Z and tenuifolin.This study provides an experimental basis for revealing processing mechanism of Polygalae Radix.