Abstract: To study the function of immunological enhancement of crude polysaccharides from Plantago asiatica L. on immunosuppressed mice, the crude polysaccharides from Plantago asiatica L. were extracted. Then, the mice were randomly divided into 6 groups of normal control, model control, high-, medium-and low-dose of crude Plantago asiatica L. polysaccharides and levamisole, which had 10 mice of each group. In addition to the normal group, the other mice were intraperitoneal injected with cyclophosphamide (80 mg/kg) to induce immunocompromised model. After successful modeling, the high-, medium-, and low-dose groups of crude Plantago asiatica L. polysaccharides were given 900, 300, and 100 mg/kg respectively, the levamisole group was given 25 mg/kg gavage, the normal and model control groups were given distilled water on equal volume. After 21 days of dosing, the serum hemolysin levels, charcoal clearance function and delayed hypersensitivity were measured, the body weight, spleen and thymus index of mice were calculated. The results showed that the suitable concentration of Plantago asiatica L. crude polysaccharides could significantly improve the clearance index of immunocompromised mice, enhance their charcoal clearance function, enhance the delayed allergic reaction of immunocompromised mice, increase the serum hemolysin level, and had a mitigative effect on weight loss, spleen and thymus atrophy of the model mice. This study showed that the Plantago asiatica L. crude polysaccharides could enhance the immune function of immunocompromised mice.