Nanoporous silver owning to large specific surface area and high densities of active sites, has a great potential for superior formaldehyde detection. Both chemical dealloying and electrochemical dealloying of Ag30Zn70 precursor alloy in 0.1 mol?L-1 hydrochloric acid solution were employed to fabricate NPS. The effects of duration time of chemical dealloying and applied potential of electrochemical dealloying on the formation of nanoporous structure and the current response of formaldehyde have been investigated. The results show that slow selective dissolution of Zn elements in intermetallic ε phase takes place during chemical dealloying of 24 h, which leads to the formation of nanoporous structure consisting of Ag and residual ε phase. Through electrochemical dealloying with applied potential of 0.1 V for 6000 s, 3D bi-continuous NPS with characteristic pore size of 80 nm was achieved. The results of cyclic voltammetry show that the oxidation current density of formaldehyde was enhanced with the increasing of formaldehyde concentration in 0.1 mol?L-1 KOH solution. The response oxidation current densities linearly depended on formaldehyde concentrations between 10~100 mmol/L, and the sensitivity of formaldehyde detection was 0.10. The present reagents of nanoporous silver had superior formaldehyde detection abilities in high concentrations of 50~100 mmol?L-1.