Abstract: The formation conditions and main components of the solid electrolyte interface（SEI film） on the surface of LiMn2O4 were studied.The results showed that the SEI film was formed in the first cycle，and the SEI film would experience a restructuring process during the second cycle； and the SEI film′s thickness was 5.08 nm.The main components of SEI were generated by chemical reaction and electrochemical reaction on the surface of electrode materials.And the main components were LiF， lithium carbonate，and organolithium compounds.Organolithium compounds included CH3OLi，CH3OCO2Li，CH3CH2Li， CH3CH2OLi，（CH2OCO2Li）2，LiCH2CH2OCO2Li，LiOCH2CH2OCO2Li and so on.

Key words: LiMn2O4, electrode material, solid electrolyte interface film