Capillary Electrochromatography (CEC) is a new microanalytical technique that uses capillary columns with a stationary phase and an electroosmotically driven mobile phase, which is considered a hybrid of liquid chromatography (LC) and capillary electrophoresis (CE), and combines the high peak efficiency of CE with the versatility and loading capacity of LC.MS can provide both molecular mass and structural information.In particular, the characterization of unknown compounds provides very useful hints for structural elucidation.The main problems of coupling CEC to MS are the interface and the column.The interface including sheathless interface, sheath flow interface and liquid junction interface.The columns used for CEC-MS have been classified into three types: packed, open-tubular and monolithic columns.