The use of room-temperature ionic liquids (RTILs) as green media for electrochemical application has attracted great attention recently. However, the effects of RTILs used as additives for electrodeposition of metals have hardly been explored. In the present work, the electrochemical deposition of copper was investigated on a pure copper plate from acid cupric sulfate solutions in the presence of RTILs (1-butyl-3-methylimidazolium tetrafluoroborate, ［bmim］BF4) additive by cyclic voltammetric technique, scanning electron microscope (SEM), and X-ray diffraction (XRD). For comparison, the electrodeposition of copper from acid cupric sulfate solutions was also investigated. The voltammograms showed that the cathodic peak potential shifted toward more negative potential and cathodic peak current increased when 1.0×10－4 mol·L-1 ［bmim］BF4 was added into acid cupric sulfate solutions. SEM images indicated that the shinning electrodeposits of copper were lamellar structure and the size of layered grain decreased with addition of ［bmim］BF4 additive. The XRD results indicated that copper deposits exhibited face-centered cubic structure and (220) highly preferred orientation. The surface-enhanced Raman scattering (SERS) activities of copper deposits were measured by using methyl orange (MO) as the probe molecules. The copper electrodeposit obtained in acid cupric sulfate solutions with ［bmim］BF4 is shown to be excellent substrate for SERS measurements, demonstrating significant enhancement and good stability. The enhancement factor was calculated to be up to 4.7×105. It was also found that copper electrodeposit stored for 60 days in air shows no significant degradation in its sensitivity.