Nanoporous copper with nano-scale pore size was synthesized by dealloying Mn-Cu alloy using a free corrosion method in acid solution. The effect of dealloying parameters, which include the electrolyte component, temperature and time of dealloying, on the residual Mn content and micro-morphology of nanoporous Cu was investigated. The results show that the nanoporous copper with a uniform three-dimensional pore structure can be created by dealloying in 0.1 mol/L HCl solution. The pore shape grows from honeycombs to three-dimensional networks with prolonging the corrosion time from 2 d to 5 d. Then with the continually increased corrosion time, the pore wall becomes coarse gradually. By increasing the temperature of the electrolyte to 60 oC, the residual Mn content is reduced obviously. The resultant nanoporous copper possesses uniform porous structures in three-dimensional network, the porosity of 57.7%, and the average pore size of 140 nm