Abstract: OBJECTIVE To investigate into the stability of triptolide,one of the active components of Radix Tripterygii.METHOD HPLC gradient elution method was used with methanol-water as the mobile phase to determine the contents of triptolide in its root,branch and leaf at different periods of its storage.RESULT Triptolide content decreased with the increase of time of its storage.CONCLUSION Triptolide content in Radix Tripterygii is not constant during its storage.