Abstract: The contents of theanine in the green tea made from Fuding Dabaicha in different origins were detected, which provided the basis for the quality identification of green tea made from Fuding Dabaicha in different origins. HPLC was used for the determination:the chromatographic column was RP-18 (particle size of 5 μm, 250 mm×4.0 mm), the flow velocity was 1.0 mL·min^-1, the column temperature was (35±0.5)℃, the determine wavelength was λ=210 nm, the sample size was 10 uL, and the mobile phase was 100% ultrapure water in phase A, being filtered by 0.45 μm aqueous phase membrane, and 100% acetonitrile in phase B, being filtered by 0.45 μm organic phase membrane. The results showed that the content of theanine in the green tea made from Fuding Dabaicha in 7 regions had a good linear relationship within the range of 0.10-0.20 mg· mL^-1, with the recovery rate of 88.80%-97.35% and RSD of 0.57%, indicating that the method had good precision and high accuracy, and could be used to detect the content of theanine in green tea. The content of theanine in green tea made from Fuding Dabaicha in 7 regions ranged from 7.00 to 26.60 mg·g^-1. And there were significant differences in the content of theanine in green tea in other origins except for Haifeng, Guangzhou and Changzhou, Jiangsu, indicating that the content of theanine was related to the tea growing regions.