Abstract: Objective: To determine antioxidant effective parts and develop a HPLC method for simultaneous determination of neochlorogenic acid and isoquercitrin in Moringa oleifera Lam leaves. Methods: The antioxidant potency of four extracts of Moringa oleifera Lam leaves,which are petroleum ether extraction,ethyl acetate extraction,total quinic acids and flavonoids,was evaluated in vitro systems. HPLC analysis was successfully conducted by using a Sepax Sapphire C_18( 250 mm × 4.6 mm,5 μm) column,eluted with a gradient of acetonitrile- 0.05% phosphoric acid with a flow rate of 1 mL / min,and detected at 330 nm.The column temperature was set at 30 ℃.Results: Quinic acids like neochlorogenic acid and flavonoids represented by isoquercitrin showed strongest scavenging capability. It showed that their scavenging activity of DPPH free radical reached 80%,when the concentration was greater than 800 μg / mL. And both of them showed higher scavenging rate for DPPH and hydroxyl radicals than petroleum ether and ethyl acetate extraction.Neochlorogenic acid and isoquercitrin showed good linearity within the test ranges.The recoveries were 98.84%,98.70%,respectively and RSD was less than 3%.Conclusions: The antioxidant effective parts in Moringa oleifera Lam leaves were total quinic acids and flavonoids.The method is simple and accurate,and could be used to identify and evaluate the quantitative determination of neochlorogenic acid and isoquercitrin in Moringa oleifera Lam leaves.