To establish a RP-HPLC method for the determination of gallic acid in Chinese herb Melastoma dodecandrum, and to evaluate the quality of the herb.The RP-HPLC analysis was achieved by using a Polaris C18 column and tetrahydrofuran-methanol-0.2% phosphoric acid (0.5:0.5:99) as the mobile phase, with a flow rate of 1.0 mL x min(-1), and detected by UV at 274 nm.The content of gallic acid was from 0.020% to 0.081%, in ten groups of M. dodecandrum collected from different locations.The method is a simple, convenient and rapid. It can be used for quality evaluation of M. dodecandrum.