Abstract: OBJECTIVE To discover the medicinal value and optimal harvest time of traditional She Medicine-Melastoma dodecandrum by studying the dynamic change of the content of gallic acid and quercetin in different parts of the herb. METHODS HPLC was applied with the chromatographic condition as follows: The chromatographic column was Agilent-SB C₁₈(4.6 mm×250 mm, 5 μm) at 30 ℃; the mobile phrase was methanol-0.4% phosphoric acid, gradient elution; flow rate was 1.0 mL·min^-1; the detection wavelength was 254 nm. RESULTS Gallic acid and quercetin existed in all parts of Melastoma dodecandrum. However, the content of active component contents in different parts varied obviously in different months. CONCLUSION The content of gallic acid and quercetin in leafs is more than stems and roots, but no content difference shows in stems and roots. Taking both gallic acid and quercetin as indices, using the parts on the ground is better for protecting traditional Chinese medicine resources. Moreover, the optimal harvest time should be in early May before flowering.