Previous studies have shown that oligodeoxynucleotides containing unmethylated CpG motifs were used as adjuvants for immunoregulation and immune response. This study was to explore the activation effects of Bifidobacteria DNA containing unmethylated CpG motifs (CpG DNA) on murine macrophage J774A.1 cells. The genomic DNA of Bifidobacteria was extracted and purified, and the methylation degree of CpG motifs was tested. The phagocytic ability of the macrophages was detected by flow cytometry. The cytokines (IL-1beta, IL-6, IL-12p40 and TNF-alpha) levels in the culture supernatants of Bifidobacteria DNA treated J774A.1 cells were assayed by ELISA. The content of nitric oxide (NO) was detected by Griess reagent. After treated with Bifidobacteria DNA for 24 h, Nile Red stain increased in J774A.1 macrophage, which suggested that the lipid metabolism increased in the macrophages. The phagocytic ability and levels of NO and cytokines of IL-1beta, IL-6, IL-12p40 and TNF-alpha were significantly higher than PBS group and CT DNA group. The results indicated that Bifidobacteria DNA could activate murine macrophages J774A.1, which could provide scientific basis for the research and application of microorganism DNA preparation.