To study the activation and mechanism of Acanthopanax giraldii Hams polysaccharide Ⅲ (AHP-Ⅲ) on mouse macrophage RAW 264.7.After RAW 264.7 macrophages were stimulated with the different concentrations of AHP-Ⅲ,the phagocytic ability was conducted by neutral red method.The release capacity of interleukin-6 (IL-6),tumor necrosis factor-α (TNF-α) and NO under different concentrations of AHP-Ⅲ stimulation were tested by the ELISA and the Griess,and the transcription level of inducible NO synthase (iNOS),TNF-α and IL-6 was determined by RT-qPCR,then were detected by Western blot phosphorylation of NF-κB signaling pathway related proteins.Compared with normal control group,AHP-Ⅲ can significantly improve the phagocytic ability of RAW 264.7 (P<0.05) within the test concentration range.Also,it can promote RAW 264.7 to secrete NO,TNF-α and IL-6 (P<0.05 orP<0.001).According to the result of RT-qPCR,in a dose-dependent manner,AHP-Ⅲ can significantly improve the expression level of IL-6,TNF-α and iNOS.Western blot suggested that after stimulation of AHP-Ⅲ,the phosphorylation level of p65,IKKβ and IκBα in NF-κB were significantly improved.The results shhowed tat AHP-Ⅲ could significantly activate RAW 264.7 mouse macrophage.