In this paper, raceanisodamine are analyzed by El mass spectrometry(EIMS),their characteristic fragment ions were obtained. The fragmentation mechanism on this component was discussed. The results showed the ring of raceanisodamine was crazed and characteristic ions m/z261 and base peak m/z94 were produced by losing free group CH2CH2OH, then its alcoholysis can create some ploy-ring ions such as m/z140 and m/z 156. These fragment act as the characters of raceanisodamine.
