A modified one-step reduction method was reported to synthesize the Sea Urchin-like Gold Nanoparticles (SU-GNPs), and the Surface-Enhanced Raman Scattering (SERS) characteristics of the SU-GNPs dependent on their surface morphology were experimentally studied. Experimental results shown that, the diameters and the thorn sizes of the SU-GNPs can be changed by adjusting the amount of silver nitrate aqueous solution added into hydrogen tetrachloroaurate trihydrate aqueous solution. When the added amount of silver nitrate was 1 μL, the as-prepared SU-GNPs had the longest thorns and the smallest diameter. And the measured UV-vis-NIR spectra exhibited that the localized surface plasmon resonance bands of the SU-GNPs were broaden with increasing of the added amount of silver nitrate. In addition, the effect of surface morphology on the SERS of SU-GNPs was investigated by using 4-mercaptobenzoic acid as a Raman reporter molecule. The results demonstrated that the SU-GNPs with smaller diameters and longer thorns gave rise to a stronger SERS enhancement.