The fermentation process of Polygonatum sibiricum-Rosa roxburghii Tratt enzyme was optimized, and its functional components, antioxidant activity, and in vitro digestive characteristics were evaluated to provide a reference for the development of food-medicine homologous products. Using P. sibiricum and R. roxburghii Tratt as raw materials and yeast and lactic acid bacteria as fermentation strains, the time, temperature, inoculum size, and sugar content were optimized using single-factor and response surface methodology, with total phenolic content and sensory score as comprehensive indicators. Under the optimal conditions, the enzyme and its freeze-dried powder were prepared. Total acid, phenolic, sugar, flavonoids contents, pH, and superoxide dismutase (SOD) activity were measured. The scavenging rates for DPPH•, ABTS+•, •OH, and O2-• were determined. An in vitro simulated digestion analysis was conducted using the freeze-dried powder. The optimal process parameters were as follows: 66 h, 34 ℃, inoculum size 4.8%, and sugar content 4%. Under these conditions, the enzyme had a sensory score of 93, total acid content of 8.64 g/100 mL, total phenolic content of 1.00 mg•mL-1, total sugar content of 1.12 mg/100 mL, total flavonoid content of 0.072 mg•mL-1, and pH of 3.12. SOD activity was 83.67 U•mL-1. The scavenging rates for DPPH•, ABTS•, •OH, and O2-• were 50.85%, 78.96%, 81.48%, and 77.12%, respectively, indicating significantly enhanced antioxidant activity. The freeze-dried powder exhibited a total acid content of 9.36 g/100 mL, total phenolic content of 1.75 mg•mL-1, and total sugar content of 3.15 mg/100 mL, which complied with the industry standard (QB/T 5760-2023). In vitro digestion showed that the total flavonoid content increased by 56.29% during gastric digestion and by 42.85% during intestinal digestion. This study successfully optimized the fermentation process for P. sibiricum-R. roxburghii Tratt enzyme. The resulting product was rich in functional components, and exhibited significantly enhanced antioxidant activity, thus providing a basis for developing functional products from food-medicine homologous plants.