We designed a new templating synthesis to produce hollow cubic Ag microboxes with net-like nanofiber structures in an ethanol system under ambient conditions. The Ag boxes are characterized by TEM, HR-TEM, FE-SEM, and XRD, which illustrates their novel hierarchical structure. The boxes are composed of metallic Ag crystallites which connect together into a net-like structure to form the walls of the boxes, and the six walls close to form the final hollow cubic Ag microbox. The fabrication mechanism of the Ag boxes is demonstrated by tracking the intermediates in the synthesis procedures. Structural analysis and comparative tests are employed to shed light on the formation mechanism of the net-like nanofiber structure. The structure-dependent surface plasma resonance (SPR) properties of the as-prepared Ag microboxes and nanofibers are described based on the UV/Vis/NIR absorption spectra.