The aim of this work was to screen both the presence of bioactive secondary metabolites using petroleum ether and methanolic extracts of green fruit (seed and skin) and cladode of Opuntia ficus indica, the quantitative determination of total phenolics, flavonoids contents, and various in vitro antioxidant activities (ferric reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl ) of hydro-ethanolic extracts. The tests of phytochemical characterization of dry matter plant including sterols/terpenes, polyphenols, flavonoids, tannins, anthraquinones, alkaloids and saponins were used in the present study. The active antioxidant, phenolic contents and flavonoids contents were determined using colorimetric method. The phytochemical characterization of Opuntia ficus indica dry seed, skin and cladode various extracts showed the presence of phenolic compounds, alkaloids (seed extract only) and saponins (skin extract only), against anthraquinones were not detected. The total phenolic contents, expressed as mg of gallic acid equivalent (GAE) per 100 g of dry matter, was found to be (73.12±1.26) mg GAE/100 g, (935.21±103.02) GAE/100 g and (390.90±14.50) GAE/100 g for seed, skin and cladode respectively. The radical scavenging activity, expressed in terms IC50 was found to be (185.85±3.57) μg/ml, (365.87±11.95) μg/ml and (1208.75±179.21) μg/ml respectively. Result for all aqueous ethanolic extracts using FRAP method was (50.06±1.07) mg AAE/100g, (318.15±1.62) mg AAE/100 g and (120.90±4.80) mg AAE/100g for seed, skin and cladode respectively. This work suggests the possibility of using dry seed, skin and cladode extracts of Opuntia ficus indica for the prevention of oxidative stress, for it has potential antioxidant activity.