[Objective]The study aimed to further explore the immunomodulatory properties of Polysaccharides from Dendrobium Officinale Leaves.[Methods]Column chromatography was used to separate and purificate polysaccharides extracted from Dendrobium Officinale.Alamar Blue Methods can detect the effect of polysaecharides of different concentrations on RAW264.7 proliferation(1000、 500、 250、 125、 25、 5μg/mL).[Results]DOP1 and DOP2,two main homogeneous polysaccharies was obtained from Dendrobium Officinale Leaves.All the polysaccharides at low concentration from 5 to 500μg/mL showed inhibiting effect on RAW264.7 proliferation compared to the control.But at the concentration of 1000μg/mL,the polysaccharide significantly promote the proliferation of RAW264.7.Moreover,all the polysaecharides were able to stimulate macrophages to produce NO in a dose-dependent manner.[Conclusion]The results above show that polysaccharides from Dendrobium Officinale Leaves have significant immunomodulatory activity in vitro.