Objective: Using passion fruit, apple and pure milk as raw materials, the optimum preparation technology and antioxidant activity of passion fruit apple flavor fermented milk were studied. Methods: Taking sensory evaluation and protein content as indicators, the effects of apple juice addition, passion fruit juice addition, sucrose addition, fermentation time and starter inoculation on sensory quality of passion fruit apple flavor fermented milk were studied by single factor test using fuzzy mathematics evaluation method. The fermentation process conditions of passion fruit apple flavor fermented milk were optimized by response surface methodology, and the antioxidant activity and various indexes of fermented milk were tested. Results: The best formula of passion fruit apple flavor fermented milk was: pure milk 82.59%, passion fruit juice 2.35%, apple juice 8.00%, sucrose 7.00%, thickener 0.06%, strain 0.002 06%, fermentation time 6.50 h. The sensory score was 8.99, and the protein content was 3.09 g/100 g. The physicochemical and microbiological tests of the fermented milk met the requirements of the relevant national standards. The results of antioxidant activity showed that the scavenging effect of passion fruit apple milk beverage on DPPH· and OH· free radicals after fermentation was higher than that before fermentation, and both showed a positive correlation with the volume concentration. After fermentation, the DPPH· and OH· were 77.7% and 45.7% respectively, indicating that passion apple flavor fermented milk had good antioxidant activity. Conclusion: The fermented milk obtained under the best formula is light yellow, with good organization state, without whey precipitation or stratification; the fermented milk also has the fragrance of passion fruit and apple with special flavor, and the proportion of sour and sweet is appropriate.