Lectins have received extensive attention due to their unique identity， immune activity and anti-cancer effects. The Pleurotus ferulae Lenzi lectin（PFLL） was isolated and purified from Pleurotus ferulae Lenzi. The objective was to evaluate the immunomodulatory effects of PFLL on the activity of macrophages. The results indicate that PFLL increased the proliferative activity， the production of nitric oxide（NO）， superoxide anion（O2-）， tumor necrosis factor （TNF-α）， interleukin-1 （IL-1） in a dose- and time-dependent manner. The production of NO， O2-， TNF-α， IL-1 were significantly induced by PFLL at a dose of 20， 100， 10， 10， 30， 20 μg/mL. A time-dependent enhancement showed that the production of NO， O2-， TNF-α， IL-1 were significantly increased within 12 h. O2- production by macrophages from PFLL-treated mice was higher than that of cells from untreated mice. Moreover， cells from both untreated and treated mice responded to phorbol 12-myristate 13-acetate （PMA） treatment； however， the O2- production was higher in the cells from treated mice than that of cells from untreated mice. Our data suggest that the beneficial therapeutic effects of PFLL may be attributed partly to its ability to modulate macrophage immune functions.