The effects of pH and applied potential on the enhancement of Surface Enhanced Raman Scattering (SEES) spectra of benzoic acid molecules adsorbed on the silver electrode surface have been studied. Experiments showed that bensoic acid molecules were adsorbed on the electrochemically roughened silver electrode surface via group -COO-. By changing the pH of solution, it was possible for benzoic acid molecules to be adsorbed on the electrode. The pH of solution and the applied potential affected the density of of adsorbed benzoic aoid molecules, and the applied potential affected the charge-transfer between group -COO- and silver electrode.