Abstract: AI Interpretation of OMS-Ortho Effect Rearrangement and its Application to identify the Positional and Geometric IsomersLi Xinming(Dalian Institute of Chemical Physics,Chinese Academy of Sciences,Dalian 116012, China)Abstract:The ortho effect rearrangements have been applied to identify positional isomers and geometric isomers in artificial intelligence(AI)interpretation of organic mass spectra(OMS). The ortho effect rearrangements form typical ions for elucidating molecular structure, so that the correct rate of the computer program output is raised by these typical ions of ortho effect rearrangements.In this paper, producting processes of ortho effect rearrangements have been discussed for the aromatic compounds,heterocyclic compounds and unsaturated acyclic compounds.Keywords:AIMS,ortho effect rearrangement,positional and geometric isomers