Abstract:The natural brown pigment of chestnut shells was extracted from chestnut shells produced in Xiuyan area by ultrasound-method. The orthogonal test was used to optimize the extraction conditions. The light stabili－ ty， heat stability， pH stability and metal ions stability were studied. The antioxidant activities in vitro of brown pigment was investigated by phenanthroline -Fe2+ and pyrogallol autoxidation method. Orthogonal test results showed that the optimal conditions of extraction of the brown pigment of chestnut shells by ultrasonic extraction method was at 75 ℃， 45 % ethanol concentration， 15 min， solid liquid ratio 1 ∶ 20（g/mL）. The yield was 7.05 %. The brown pigment of chestnuts shells was good at light， heat and pH resistance. It was stable against Na+，K+， Ca2+，Zn2+，Mg2+，Ba2+ while was sensitive to Fe3+，Pb2+，Cu2+. In the setting concentration range， the antioxidant activities of brown pigment of chestnut shells increased with the elevation of concentration and were lower than that of VC. The clearance rates of hydroxyl free radical and superoxide anion of 2.0 mg/mL brown pigment of chestnut shells were 55.9 % and 65.2 %.