Passiflora edulis (P. edulis) is a medicinal and food plant with several pharmacological activities, but its leaves are not well exploited and utilized. The preparation procedure of Passiflora edulis leaf extract (PELE) was optimized using the orthogonal design on L9(4³) parameters based on the transfer rate of orientin from raw material and the quality control methods were established to a method for determining the total flavonoid content by UV-vis and the orientin content by HPLC. The evaluation of immunomodulatory and anti-inflammatory activities of the PELE were used by establishing a mouse model of immunosuppression and paw edema. The results showed that 80% ethanol, 60 min extraction at 90°C and 1:8 ratio was the best extraction process for PELE with a transfer rate of 11.15 ± 0.05 %. The total flavonoids and orientin content in PELE were measured to be about 67.79 ± 5.51 and 3.89 ± 0.03 mg/g, and the transfer rate of orientin was 56.49 ± 0.41%. In the immunosuppression model, PELE pretreatment delayed the atrophy of immune organs and reversed the down-regulation of immunoglobulin IgA, IgG, IgM and pro-inflammatory factors TNF-α, IFN-γ, IL-2, IL-10 levels in mice. In a mouse paw edema model, PELE significantly reduced paw swelling and also showed down-regulation of pro-inflammatory factors TNF-α, IL-1β, IL-6 and up-regulation of anti-inflammatory factors IFN-γ, IL-2, IL-4, IL-10. In conclusion, PELE has good immunomodulatory and anti-inflammatory activities and is a good candidate for the development of drugs for the treatment of related diseases.