A rapid determination method of the active xanthones in Garcinia mangostana was developed by supercritical fluid extraction rapid preparative chromatography-mass spectrometry.The active xanthones in Garcina mangostana were extracted by supercritical fluid extraction technology with alcohol as entrainer,and two xanthones,α-mangostin and gartanin,were separated from the crude extract through the device of rapid preparative chromatography and identified by mass spectrometry.The purity of two isolated compounds was not less than 90% via detection of HPLC/DAD.Meanwhile,the fragmentation mechanisms of two compounds were studied by electrospray ionization tandem mass spectrometry(ESI MSn).