In this study, we prepared a series of photoluminescent gold nanodots (Au NDs) from gold nanoparticles (3 nm) via etching with 11-mercaptoundecanoic acid (11-MUA) under various ionic strengths or various co-accessing alkanethiol (RSH) ligands. We have demonstrated that self-assembly of 11-MUA molecules on Au NDs under various salt concentrations, and co-immobilization of (11-mercaptoundecyl)trimethylammonium bromide/11-MUA or α-lipoic acid/11-MUA on Au NDs play significant roles in determining particle sizes and thus their optical properties, such as quantum yield, absorption and emission wavelength, and emission lifetime. Our findings reveal that the photoluminescence of Au NDs depends on the ligand density, chain length and electron donation of alkanethiols, and the core size.