Abstract: A method called pulse-pressurized capillary column is used for preconcentration and separation of Li, followed by determination of trace Li in geological samples by ID-ICP-MS. The key points of the method are: stationary phase with micro size 200～400 mesh resin, capillary column with inside length of 50 mm and diameter of 1.5 mm, and mobile phase pulse-powered by pressurized argon gas. The dull volume of the column bed can be reduced to minimum and high preconcentration efficiency is able to be obtained. Elution volume is only 1.0 mL, but recovery over 97%. Both inorganic material and cation exchange resin are tested as stationary phase in this work. The results show that cation exchange resin is better than inorganic material for Li separation, even though both materials are of high preconcentration ability. The method is used to preconcentrate Li and separate matrix in geological samples, and contents of Li in those samples determined by ID-ICP-MS, giving precise of 3% and good accurate results.