Ag nanoporous structure has been fabricated by dealloying of Al-20 at.%Ag in 2 M HCl at room temperature. We describe the changes of phase constitution and microstructural morphology during the dealloying. The bi-phase structure of alpha-Al and gamma-Ag2Al was obtained using melt-spinning, and considerable amount of gamma-Ag2Al was suppressed. According to the phase quantitative analysis, 5.6 % gamma-Ag2Al was precipitated at the grain boundary and inside the grain. At the early stage of dealloying process, the deep channel occurred at the interface of alpha-Al and gamma-Ag2Al due to concentration gradient of Ag; and then, alpha-Al was preferentially dealloyed with comparison to gamma-Ag2Al and formed 3-dimensional nanoporous structure which showed the open-pore/ligament bi-continuous structure. After 720 min, gamma-Ag2Al was dealloyed and formed 2-dimensional pored-wall structure. At the end of dealloying reaction, the initial grain/intermetallic wall structure was maintained. The Ag nanoporous structure was gradually coarsened with the increase of dealloying time, from 25 +/- A 5 nm at 20 min to 113 +/- A 22 nm at 720 min. The calculated coefficient of surface diffusion of Ag was 2.34 x 10(-17) m(2)/s. The surface diffusivity of Ag obtained in this study showed two orders of magnitude higher than the Au dealloyed from Au-Ag precursor at the similar temperature.