Abstract:The composition of free amino acids in different tea （green tea，black tea and oolong tea）is analyzed.Each dried pretreated tea（0.25 g）was extracted by 10mL pure water in a designed temperature（90 ℃），extraction time 20min.then filtrated through 0.45 μm cellulose membrane，pretreated by SPE column.Take 70 μL samples and 10 μL O-phthalaldehyde（OPA）derivatization liquid in water bath reaction at a temperature of 25℃，2 minutes later were determined by high performance liquid chromatography（HPLC），chromatographic condition was performed on a C18column，DAD detector，detection wavelength was 338 nm.The mobile phase A was the methanol acetonitrile water solution，and the mobile phase B was the phosphate buffer solution.The results showed that the solid phase extraction cartridges（SPE）column treatment could effectively remove the influence of chromatographic peaks of impurities，and the HPLC method could be effective for the separation and determination of 17 kinds of amino acids in different tea，the content of amino acid in green tea was higher than fermented tea，especially aspartic acid，glutamic acid，and the content of L-Theanine in three kinds of tea was significantly different.