The study was carried out to determine the effects of sesquiterpene extraction conditions from Cyperus rotundus L. on the antioxidant activity of the extract. The part of the rotundus used is the roots. The study investigated the impact of solvent type, solvent concentration, solvent/material ratio, extraction temperature, and time on antioxidant ability (via the percentage of free radicals scavenging). The results showed that the suitable conditions were methanol 80% with a material/solvent ratio of 1/30 (w/v) at 50 °C for 4 hours. The obtained extract revealed high free radical scavenging activity with 93.41%. The results indicate that sesquiterpene extract from C. rotundus is a potential source of natural antioxidants.