Abstract: The researches have three main branches: (1) ESI-FTICRMS is used for structural characterization of the reactive ionic intermediates of Pd0 catalyzed reaction of allenes with boronic acids in the presence of AcOH; (2) Tandem mass spectrometry is used to predict the chemical transformations of 2-pyrimidinyloxy N-arylbenzyl amine derivatives. The strategy “from gas phase to condensed phase” means to collect and summarize the chemical information of the compound in the mass spectrometric process to provide valuable clues of possible chemical analogous transformations or reactions of the compound in solution; (3) Characterization of the key radical cationic intermediates in the reaction of selectfluor with multi-phenyl-substituted olefins was achieved by ESI-MS/MS, which supports the SET mechanism in this electrophilic fluorination reaction.