The use of plant extracts and phytochemicals can be of great significance in therapeutic treatments, and control of many pests and microorganisms globally. Nanotechnology and green synthesis of the nanoparticle is the novel trend for use in different fields. In this study, Copper Oxide nanoparticle was synthesized by a green technique by using Achillea fragrantissima and Nigella sativa extracts.  The Characterization of CuO nanoparticles was carried out by TEM and DLS techniques. The effect of nanoparticles as larvicidal, and molluscicidal is more potent than using extracts themselves. The values of LC50 of Cu nanoparticle and Achillea fragrantissima extract against Pirenella conica snails were 5.65 and 279.53 ppm respectively. The larvicidal effect against Culex pipiens mosquitoes LC50 values were, 0.98 and 79.69 ppm for Cu nanoparticle and Achillea fragrantissima extract, respectively.  Also, CuONPs from both ethanol and petroleum ether extracts appear high inhibitory effect against all tested organisms compared to that of crude extracts. It is observed that CuONPs demonstrated a high degree of antibacterial activity for S. aureus and P. aeruginosa and showed activity against C. albicans fungus.