This study aimed to the determination of antioxidant, anti-inflammatory, and anticoagulant activities of phenolic compounds present in olive oil mill wastewater (OMW) issue from the cold extraction of olive oil from Khenchela eastern of Algeria.After polyphenols extraction, a quantity and quality analysis by LC-MS was made. The LC-MS (liquid chromatography–mass spectrometry)results were revealed the presence of 20 phenolic compounds in theextract of OMW which were: (quinic acid, gallic acid, protocatechuic acid, caffeic acid, p-coumaric acid, rutin, transfrolic acid, hyperoside (quercetin-3-o-galactoside), luteolin-7-o-glucoside, naringin, 4.5-di-caffeoyquinic acid, quercetrin(quercetin-3-o-rhamonosid), apegenin-7-o-glucoside, salviolinic acid, kampherol, quercetin, naringenin, apegenin,cirsiliol, and cirsilineol). The results of antioxidant activity with DPPH(2,2-diphenyl-1-picrylhydrazyl), ABTS+ (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid), and FRAP (ferric reducing ability of plasma)showed that the IC50(half-maximal inhibitory concentration) were(9.62 ± 0.28µg/mL, 7.10 ± 0.11µg/mL and 3.59 ± 0.24µg/mL)respectively. The extract of OMW was found to exhibit the highestinhibitory effectanti-inflammatory activity usinginhibition of protein denaturation(IPD) and membrane stabilizing potential (MSP) tests (80.46 ± 3.81; 87.43 ± 0.66 µg/mL) more than the standard used. In addition, the extract had the best anticoagulation activity in the endogenous and exogenous pathways (44.77 ± 0.25s; 15.84 ± 0.12s). Based on these results, it is right to conclude that OMW is an important source of natural phenolic compounds that have important antioxidant, anti-inflammatory, and anticoagulant activities.