Arundo donax (Family Poaceae) 70% ethanolic ethanolic extract was subjected to phytochemical analysis, which revealed the existence of 16 natural flavonoid compounds. Most of these compounds were extracted and characterized using chromatographic methods, chemical degradation, and spectral data (1H NMR, 13C NMR and LC-ESI-MS). This ethanolic extract and its nanoparticles are employed in the assessment of their biological activity. The A. donax ethanolic extract was evaluated for the creation of silver nanoparticles, which gave nanoparticles less than 20 nm. Using DPPH (2,2-diphenyl-1-picrylhydrazyl) as the stable radical method, the antioxidant activity of ethanolic extract and its nano was investigated. The results showed a high radical scavenging activity for A. donax ethanolic extract, which has a chelating power inhibition of about 65% more than AgNPs of 35% and its logic according to the principle of free radical mechanism. According to the antimicrobial study's findings, the nano extract of A. donax has greater antimicrobial activity than the ethanolic extract against gram-positive bacteria like Bacillus cereus and Staphylococcus aureus, as well as gram-negative bacteria like Escherichia coli and pathogenic yeast like Candida albicans. At a concentration of 100 g/ml, their cytotoxic activity against the human cancer cell lines A-431 (skin cancer), PC3 (prostate cell line), HCT-116 (colon cell line), and BJ-1 (normal skin fibroblast) revealed that all of the tested samples had a minimal to non existent cytotoxic effect on the cancer cell lines, whereas the nano extract had a significant cytotoxic effect.