Abstract: On the basis of electromagnetic field theory and magnetic energy storage,the secondary edge equivalent airgap and edge leakage of high speed line induction motor （LIM） were presented. The characteristic of this type of machine was analyzed by using of the equivalent circuit considering secondary edge leakage. Then three-dimensional field analysis by Maxwell 3D software was used to predict electromagnetic force. The prototype machine is designed and experimental results verify the correctness and effectiveness of the formulas.