Nanosized colloidal gold was prepared by the reduction of chloroauric acid with trisodium citrate in aqueous solution with microwave heating method. The diameters of gold nanoparticles were from 13 to 70 nm with the ratio of the trisodium citrate and chloroauric acid. With rhodamine 6G (R6G) as the detection molecules, the SERS properties of gold colloid were studied. Experimental results show that the gold colloids with 50-60nm particle diameters are excellent SERS substrates and sodium chloride (NaCl) can improve gold colloid's surface-enhancement effect.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.