To investigate the in vitro immunostimulating effects of Lentinan and Astragalus polysaccharides in cellular and molecular levels in the Cyprinus carpio, the macrophages and the peripheral blood leukocytes were isolated from the head kidney and blood of Cyprinus carpio respectively through Percoll gradient density centrifugation, cultured and exposed to different concentrations of Astragalus polysaccharides and Lentinan. The proliferation of the peripheral blood granulocytes, respiratory burst of macrophage and IL-1βmRNA expression of macrophages were analyzed by MTT ,NBT reduction, Griess reaction and Real time PCR respectively. Results showed that proliferation of peripheral blood leukocytes after 24 h incubation with Astragalus polysaccharides at 10,100µg·mL^-1 and Lentinan at 100,1000µg·mL^-1 was markedly stimulated. Lentinan at 1, 100,1000µg·mL^-1 could induce superoxide anion in macrophages markedly, while Astragalus polysaccharides had no effect. Reduction of nitric oxide of head kidney macrophages (HK macrophages) after 96 h incubated by polysaccharides showed Astragalus polysaccharides at 10µg·mL^-1 had conspicuous effect on nitrogen burst activity of macrophages but Astragalus polysaccharides had no effect, moreover both Astragalus polysaccharides and Lentinan at 1000µg·mL^-1 inhibited the nitrogen burst activity at higher doses. The expression of interleukin-1βin the HK macrophages after 24 h stimulation by the two polysaccharides showed Astragalus polysaccharides and Lentinan stimulated IL-1βexpression in carp head kidney . It is suggested that Astragalus polysaccharides and Lentinan could modulate the immune response of Cyprinus carpio.