Abstract: This paper deals with the quantitative determination of Farrerol in MAN-SHANHONG leaves by TLG and subsequent reaction with NaOH reagent.Macerate 2.0g of powdered sample with 20.0 ml ether for 4～5 hours. Take exactly 10.0ml of the filtrate, evaporate and dissolve the residue in 2.0ml methanol. Spot 25μl of the prepared sample solution on a silica gel plate containing NaHSO₃, then develop with a mixture of chloroform-methanol (7:0.5). The spots are located by UV light, and scraped into 10ml glass stoppered test tubes. Add accurately 6.0 ml of 1.0 NNaOH solution. Mix well and warm the mixture at 50℃ for 5 minutes. Cool to room temperatare, centrifuge and take the supernatant solution for colorimetry at 420 nm against a reagent blank.The method is simple, sensitive and reproducible, it has been applied to various kinds of preparations.