Colloidal gold nanoparticles with a broad size distribution were prepared by laser ablation of a gold metal plate in an aqueous solution of sodium dodecyl sulfate (SDS) and were fragmented under irradiation of a 532 nm laser at different SDS concentrations and laser fluences. Gold nanoparticles with a desired average size (1.7-5.5 nm in diameter) were prepared by tuning properly the surfactant concentration and the laser fluence. The concentration of SDS was found to be higher than a critical micelle concentration so as to gain a significant size reduction and to obtain stable final products. Laser ablation in combination with the laser-induced size control provides a versatile full physical preparation method of size-selected gold nanoparticles.