Objective:To establish a simple

accurate method of HPLC to determine the gallic acid content of Polygonum capitatum

and to analysis 48 populations in different germplasm resources.Method: The method was developed with the condition as follows:XB-18 C18（4.6 mm × 250 mm

5 μm）

acetonitrile-0.4% phosphoric acid（4∶ 96） as the mobile phase with the speed of 0.8 mL.min-1 and the detection wavelength was 220 nm.Gallic acid was detected in 48 populations with 229 samples.Result: The linear range of gallic acid was 10.24-102.40 ng（r = 0.999 9） with the average recoveries of 97.32%

RSD 0.52%.The gallic acid content was 0.594 6%-0.147 5% in every sample

and was 0.131 3%-0.330 6% during 52 populations.Conclusion: The method is simple

specific

and suitable for the determination of the gallic acid content in P.capitatum.There are some differences in gallic acid contents during populations and whithin populations

especially

it was significant differences in some populations

such as Yunnan-tengcong

Guizhou-taijiang

Guizhou-nayong

Guizhou-yuqing

Guizhou-qinglong and Guizhou-bijie.It had higher contents of gallic acid in Taijiang-laodun

Nayong-yangchang

Yuqing-baini

Shibing-niudachang populations

Guizhou province

and they should continue to study as suitable growth areas for artificial cultivation of P.capitatum.