Organic acids are important metabolites participating in the biochemical metabolism of tea， which are affect the aroma and taste of tea. In this study， the method for determination of organic acids was optimized. The system conditions： mobile phase： isocratic elution with 10 mmol/L KH2PO4， pH 2.65， flow rate： 0.8 mL/min， injection volume： 5 μL， determine wavelength： 210 nm， column temperature： 30 ℃. This method can simultaneously detect 9 organic acids including oxalic acid， tartaric acid， quinic acid， pyruvate， malic acid， lactic acid， acetic acid， citric acid， fumaric acid and succinic acid. The contents of organic acids in white teas were detected by the optimized method. The results showed that the content of organic acid in Baimudan was the highest， while that in Shoumei was the lowest. Citric acid and quinine acid were the main components that affected the total amount of organic acids. The contents of pyruvate， acetic acid and citric acid were decreased with the decrease of tenderness， while malic acid was increase. The highest content of oxalic acid was showed in Baimudan and Gongmei. During withering process in white tea， active organic acid metabolism occurred during the first 2/3 period of withering process. The contents of oxalic acid， quinine acid， malic acid and acetic acid increased significantly in the first half of withering， pyruvate and fumaric acid decreased first and then increased during withering， while malic acid decreased first and then decreased.