Abstract: Objective To establish a model of dengue virus infection in mice and to detect the level of dengue-2 virus in mice'blood.Methods The standard preparation of the plasmid was constructed.The copies of virus in the blood were detected with real-time PCR(absolute quantitation)after the C57BL/6 j mice had been inoculated with Den-2 NGC strain (2×108 copies/mouse and 2×109 copies/mouse)through peritoneal in jection.Results The copies of virus in the blood were detected after the C57BL/6 j mice infected with DEN 22 NGC strain.The virus load in the grous of 2×108 copies/mouse and 2×109 copies/mouse at the first,third and fifth day was 1.05×103.5-1.05×103.7,1.05×103.8-1.05×103.9,1.05×103.5-1.05×103.7 and 1.4×103.5-1.4×104.4,1.4×106.9-1.4×107.32,1.4×103.8-1.4×104.8 copies/mL,respectively.Conclusion The level of the virus in the blood raises in the first day after the mice infected with DEN-2 and reaches the summit at the third day,then decreases at the fifth day.