Opuntia ficus-indica is well-known in Algeria for its nutritional and therapeutic properties. Our study aims to determine the physicochemical properties, the functional groups and the antioxidant activity of cactus seed oil and thus contribute to the valorization of seeds.  The extraction of prickly pear seed oil with cold-press provided a yield of 4.26± 0.93%. The evaluation of the its physicochemical parameters by the norms of AFNOR yielded the following results: density: 0.908± 0.00030 kg/dm; RI: 1.4714±0,00010; AV: 1.4± 0.09 mg KOH/g; IV: 114.08± 0.67 g I 2 /100 g; SV: 188.94± 0.58 mg KOH / g; ES: 187.54±0.49 mg KOH/g; PV: 1.56 g O2 /g; chlorophyll number: 1.076 and Carotenoids number: 0.315. FTIR spectrum was used to determine the functional groups and type of associated vibrations in the extract oil, which was scanned in the range (4000-400) cm -1. The FTIR results showed that the oil extract contains fatty acid methyl esters, revealing functional groups with ranges of properties, H- C = O, -(CH2) n -, C-O, C = C and C = O in the spectrum. The analysis of antioxidant activity using DPPH and FRAP methods showed that the OFI seed oil had a significant activity in capturing free radicals (IC50= 0.050 mg/mL), (EC50 = 0.123 mg/mL) respectively. We conclude from this current study that this oil can be used in folk medicine.