Abstract: Objective:The effect of immune enhancecement was researched on the effect of Codonopsis lanceolata polysaccharide on mouse spleen lymphocytes and RAW 264.7 for exploring the effect of its immune enhancement. Methods:Conventional preparation of polysaccharide from Codonopsis lanceolata and mouse splenocytes or RAW 264.7 were respectively inoculated with the concentration of polysaccharides about 1000,500,250,125μg/mL. Adopted the ELISA method to exam the cell supernatant. Studied the change of IL-2,IFN-γ,IL-6,TNF-α concentration of cell factor secreted by codonopsis lanceolata polysaccharide in induced mouse splee n lymphocytes. Adopted MTT method to study the effect of polysaccharide on the proliferation of RAW 264.7. Measure the content changed of the NO by Griess method. The formation of iNOS mRNA was measured by RT-PCR. Results:Compared with the normal group,the crude polysaccharides of Codonopsis lanceolata significantly increased the secretion of IL-2,IFN-γ,IL-6,TNF-α and NO,and the difference was very significant(p<0.01). The proliferation of RAW 264.7 was significantly different(p<0.05). Compared with the normal group,iNOS mRNA increased significantly. Conclusion:Codonopsis Codonopsis lanceolata polysaccharide can enhance the activity of T cells synergistically with ConA,and can also participate in the activation of smononuclear macrophages which was a positive regulation of specific and non specific immune activities.