Mercury（Hg2+） ions deposited on the surface of gold nanoparticles（AuNPs） absorbing single strand DNA（ssDNA） can promote the peroxidase-like activity of AuNPs.Based on this，a highly sensitive detection of Hg2+ was developed.Here it was found that ssDNA can promote the activity of AuNPs-Hg2+ mimetic peroxidase due to the adsorption of ssDNA on the AuNPs surface.The catalytic activity of AuNPs-Hg2+ mimetic peroxidase increases with increase of ssDNA concentration.The ssDNA-AuNPs-Hg2+ mimetic peroxidase can be applied in the detection of Hg2+ in a linear range of 10-1 000 nmol/L with a detection limit as low as 3.0 nmol/L under optimized condition.The method was simple，rapid，low cost and stable，and had high application potential to detect Hg2+ in the environment，food and other samples.