Abstract: Contents and structure of anthocyanins in purple pakchoi were identified by high performance liquid chromatography-electrospray ionization tandem mass spectrometry ( HPLC-ESI- MS) .Two kinds of anthocyanins were found in“New ZIGUAN”purple pakchoi.The mainly existence of anthocyanins were acylation form, there were10 anthocyanins and 9 isomeric compounds.The total anthocyanin content of purple pakchoi was 51.36μg /g·fw, which was calculated as the reference of cyanin- 3, 5- diglucoside standard.Among them, cyanidin content was50.71μg /g·fw, accounting for 98.73%.And delphinidin content was 0.65μg /g·fw, accounting for 1.27%.Cyanidin-3-feruloyl-sophoroside-5-malonyl-glucosidase was the major anthocyanin, accounting for 31.85% ( 16.36μg /g·fw) of the total anthocyanins.