Objective: The aim of this investigation was to study the detoxification of fruit of Medicine Terminalia (FMT) on root of Kusnezoffii Monkshood (RKM). Method: Ultrasonic extraction was applied to extract aconite alkaloids in RKM and RKM-FMT powder. ESI-MS was adopted to monitor the alkaloids in diethyl ether extract of RKM and the blend of RKM with FMT

in acidic diethyl ether extract of RKM

in absolute ethanol extract of RKM and the blend of RKM with FMT

in absolute ethanol extract of the residue of blend of RKM with FMT after extracting by diethyl ether

as well as diethyl ether extract of the blend of diester-alkaloids with FMT. Result: There were monoester-alkaloids

diester-alkaloids and lipo-alkaloids in diethyl ether extract of RKM

and the relative abundance of diester-alkaloids was the highest among them. In diethyl ether extract of the blend of RKM with FMT

the relative abundance of diester-alkaloids decreased as the FMT amount increased

moreover

that of lipo-alkaloids became the highest when the FMT amount was three times as that of RKM. In acidic diethyl ether extract of RKM

the lipo-alkaloids were detected as the basic peak. The relative abundance of all alkaloids in absolute ethanol extract of RKM was the same as that of the blend of RKM with FMT. FMT didn't affect the relative abundance of the alkaloids in diethyl ether extract of the blend of diester-aconite alkaloids with FMT. On the basis of the above results

we could conclude that FMT can restrain the dissolution of dister-alkaloids of RKM in diethyl ether

however

in absolute ethanol the effect was related to the amount of added FMT. Acid condition could also restrain the dissolution of dister-alkaloids in diethyl ether. Conclusion: Under low polarity condition

detoxification of FMT on RKM was through restraining the release of diester-alkaloids in diethyl ether. This research is significant for studying antidotal method of RKM as well as clarifying the mechanism of synergy of formula which contains both RKM and FMT.