In this study, a facial synthesis route for cubic Ag micro structure with well-defined hollow interior was developed. The fabricated hollow micro-cages were applied as the substrate for the detection of ultralow concentration of crystal violet (CV)-a poisonous organic pollutant. The substrate exhibits optimum SERS performance with a detection of 10−6 M of CV due to the unique hollow morphology, proving that it is a good candidate for SERS detection in the chemical and environmental field.