Abstract With the advancement of vaccine technology, the need for safe and effective adjuvants has become increasingly important. Saponin-based compounds, known for enhancing antigen presentation and immune activation, are widely used in various vaccines. However, existing saponin adjuvants often suffer from cytotoxicity and hemolytic issues that limit clinical application. In this study, we designed and synthesized a novel saponin conjugate, MH-b, by linking phytosphingosine to the saponin core via an amide bond, aiming to retain immunostimulatory activity while improving biocompatibility. MH-b was synthesized using a protecting group strategy and glycosylation reactions, and its structure was confirmed by NMR and mass spectrometry. In animal experiments, C57BL/6J mice immunized with MH-b and ovalbumin showed no significant toxicity, and body weight remained stable. ELISA results revealed that MH-b significantly enhanced OVA-specific IgG1 antibody responses, with titers exceeding those of the control group by more than threefold. Additionally, MH-b increased the levels of IL-4 and IFN-γ, suggesting the potential to induce both Th1 and Th2 responses. Overall, MH-b demonstrates excellent safety and immunoenhancing properties, highlighting its promise as a next-generation vaccine adjuvant candidate.