Abstract: A fruit and vegetable fermented beverage with strong antioxidant activity was made from raw materials ( shaddock and jerusalem artichoke) which mixed fermentation by koji, Saccharomyces cerevisiae, Lactobacillus plantarum and Acetobacter. The clarification process of fruit and vegetable juices was determined by orthogonal experiment, and the changes of physical and chemical indexes and antioxidant substances in the fermentation process were monitored. The antioxidant activity of fruit and vegetable fermented beverage was detected by DPPH method, superoxide anion method and reducing ability respectively. It showed that the light transmittance of fruit and vegetable beverage reached 85.80% with 0.08% of pectinase concentration of fruit and vegetable juices, 55 ℃ and 50 min. At the end of the mixed fermentation of fruit and vegetable beverage, the total sugar increased 28.41% to 3.973 g/L, vitamin C was 9.454 mg/100 m L which increased 23.81%, naringin was 0.150 mg/m L, increased by 23.97%, and inulin was 1.229 mg/m L which increased 63.65%, compared to the fruit and vegetable juices without adding the koji.The clearance rate of DPPH by fruit and vegetable fermented beverage was 95.50%, which was higher than glutathione but lower than VC.The clearance rate of superoxide cations was 73.90%, which was higher than glutathione and VC.Reducing capacity was significantly higher than glutathione but lower than VC.