In this work, we reported synthesis of ZnO nanoparticles (ZnONPs) by green procedure. A simple and effective synthesis of ZnONPs was performed by Dittrichia graveolens aqueous extract. The effect of three parameters including pH of the Zinc solution (4.0, 6.0 and 8.0), time (40, 60 and 120 min) and extract ratio (25 and 75 %) were studied and optimized using Response Surface Methodology (RSM). The ZnONPs were characterized by UV–Vis, FTIR and FESEM methods. The size of particles were around 100 nm. This new eco-friendly synthesis of ZnONPs is a convenient technique for large scale commercial manufacture of ZnONPs.