Abstract:  Flavones and catechins are critical chemicals associated with the sensory quality and biological activity of tea. This study aimed to establish an applicable method for the determination of total flavonoids in teas. Specimens of commercially available teas of different categories were extracted with 70% methanol followed by colorization with a NaNO₂-Al(NO₃)₃-NaOH solution. Using rutin as the reference, a spectrophotometric method for absorbance measurements at 510nm was established and validated. For comparison, the polyphenol contents in 15 samples of green, white, oolong, and black teas were determined at the same time by the conventional Folin-Ciocalteu method. A high linear correlation on the total flavonoids measured by the absorbance and the polyphenols by the chemical determination was found in the rutin concentration range of 0.2-1.0mg·mL^-1 with the regression equation of Y=1.2465 X+0.0074 (R²=0.9997). The newly developed spectrophotometric method showed RSDs on the measurement precision at 1.17%, on the repeatability at 2.92%, on the stability at 6.01%, and on the 84.35% average recovery rate of spiked standards at 4.15%. The flavonoid contents in the 15 samples ranged from 5% to 10%, and polyphenols from 7% to 15%. The total flavonoids contents in the 4 tea categories ranked as green tea/white tea>oolong tea>black tea. A bivariate correlation analysis showed that the content of total flavonoids positively correlated to that of tea polyphenols with a Pearson correlation coefficient of 0.874. The proposed methodology was deemed simple, precise, repeatable, and stable for the total flavonoids determination on teas.