In this study we report the effect of laser energy on the size and morphology of the gold nanoparticles (GNPs) prepared in deionized water by pulsed laser ablation. The optimum conditions at which gold nanoparticles obtained with controllable average size have been reported as these parameters affected the size, distribution and absorbance spectrum. Effect of energy was studied. The laser energy was divided into three regions (low, middle and high). A noteworthy change was observed at each region, as the average size ranging from 30 nm at low energy to 60 nm at high energy.