Abstract: The pigment from pitaya peel was extracted by ethanol, orthogonal experiment was used to optimize the extraction process, antioxidant activities in vitro were evaluated in three systems as follow:hydroxyl radical (·OH) scavenging capacity, DPPH· scavenging capacity and superoxide anion radical scavenging capacity. The results showed that the optimum parameters of extracting pigment from pitaya peel for DPPH· scavenging capacity were 90% of ethanol as extraction solvent, 3h extraction time, 1∶16 (g/mL) liquid materials at 25℃ and DPPH· scavenging capacity was 94.68%. The 50% inhibitory concentrations (IC50 value) on scavenging DPPH·, ·OH and O-2· were respectively 2.09, 46. 0 and 2.44mg/mL. The pigment extraction exhibited a concentration-dependent radical scavenging activity in three systems.