Objective: Study on the content of active compounds in water extracts of Ephedra-Cinnamomi by compatibility of different ratio and to explain the mechanism of this compatibility. Method: The content of norpseudoephedrine (NMP)

norephedrine (NME)

ephedrine (E)

pseudoephedrine (PE) and methylephedrine (ME)

which are the major active compounds of Herba Ephedra

were analyzed by gas chromatography-mass spectrometry (GC-MS). The content of coumarin

cinnamic alcohol and cinnamaldehyde

which are the major active compounds of Cortex Cinnamomi in the extracts were analyzed by high performance liquid chromatography (HPLC). Result: The content of NMP

NME

E

PE

ME

coumarin

cinnamic alcohol and cinnamaldehyde in water extracts of pairmedicine Ephedra-Cinnamomi was lower than that of single decoction. Conclusion: Combined Ephedra with Cinnamomi

the dissolution of chemical compounds was inhibited with each other in water extracts.