A high performance liquid chromatographic (HPLC) method was used to detect anthocyanin extract from onion in 10 regions and the common peaks were identified. The Pearson Correlation Analysis and Grey Relation Aanlysis were used to analyze the correlation between its common peaks, content, antioxidant activity (the ability to scavenge DPPH, ABTS free radicals) and AChE inhibitory activitiy. Result: According to the characte-ristics of HPLC and relative retention time of different batches of onion anthocyanins, and the characteristic chromatograms of onion anthocyanins were established. The chromatograms of anthocyanin extract from onion in 10 different regions were similar to the control fingerprints, the similarities were 0.986 to 0.997, greater than 0.9. Six common peaks were identified as characteristic absorptions peaks, and the first peak was anthocyanin (Cyanidin-3-O-glucoside). PCA and GRA showed that the six commom peaks had a good correlation with the content, antioxidant and AChE inhibitory activites, and they aceted synwegistically on biological activity.