OBJECTIVE： To establish the fingerprint of the ethanol e xtract from Melastoma dodecandrum ， to study spectrum-effect relationship of its antioxidant activity. METHODS ：HPLC method and Similarity Evaluation System of TCM Chromatographic Fingerprint （2012 edition）were used to establish the fingerprints of 15 batches of ethanol extracts from M. dodecandrum，and heir similarity was evaluated. The common peaks were identified by comparing with substance control. DPPH free radical scavenging method ，ABTS free radical scavenging method and total antioxidant capacity determination method （FRAP） were used to determine antioxidant activity in vitro of 15 batches of ethanol extracts from M. dodecandrum . Principal component analysis，bivariate correlation analysis and partial least squares regression analysis were used to study the spectrum-effect relationship of the antioxidant activity of the ethanol extracts from M. dodecandrum . RESULTS ：Totally 20 common peaks were identified in HPLC fingerprints of 15 batches of ethanol extracts from M. dodecandrum ；its similarity with the control fingerprint was not less than 0.831；it was identified that peak 3 was gallic acid ，peak 13 was vitexin ，peak 17 was rutin and peak 19 was ellagic acid. The IC 50 values of DPPH radical scavenging method of 15 batches of ethanol extracts from M. dodecandrum were 21.98-57.87 μ g/mL，that of ABTS radical scavenging method were 40.94-101.88 μ g/mL，the results of FRAP method were 0.19-0.48 mg/mL. Principal component analysis showed that the contribution rate of IC 50 variance of DPPH was 80.77％. Bivariate correlation analysis showed that the peak areas of peak 2 （positive correlation ） and peak 11 （negative correlation ） were significantly correlated with antioxidant activity （P＜0.05）；partial least squares regression analysis showed that ，the variable projection importance （VIP）in descending order was peak 11＞peak 2＞peak 16＞peak 15＞peak 12＞peak 13＞peak 18，and their VIP values were greater than 1. Peaks 2，13，15，16 and 18 were positively correlated with antioxidant activity ，and peaks 11 and 12 were negatively correlate d with antioxidant activity ，and the absolute value of standardized regression coefficient were greater than 0.1. CONCLUSIONS ：Fifteen batches of ethanol extracts of M. dodecandrum have antioxidant activity in vitro . The compounds corresponding to common peaks 2，11，12， 13，15，16 and 18 may be the material basis of antioxidant activity of M. dodecandrum .