Objective To explore the extraction efficiency and quality of sea buckthorn seed oil obtained by subcritical butane extraction.Methods Taking extraction yield as the evaluation index, response surface methodology was adopted to optimize the process parameters for subcritical butane extraction of sea buckthorn seed oil (Y-sea buckthorn seed oil). The extraction yield, physicochemical properties (acid value, peroxide value, iodine value, saponification value, and insoluble impurities), fatty acid composition, lipid concomitants (vitamin E, phospholipids, tocopherols, squalene, and sterols), total phenols, total flavonoids, DPPH radical scavenging rate, ABTS⁺ radical scavenging rate, and FRAP antioxidant capacity were compared and analyzed across sea buckthorn seed oils extracted by supercritical CO₂ (C-sea buckthorn seed oil), ultrasonic-assisted extraction (E-sea buckthorn seed oil), and traditional solvent extraction (S-sea buckthorn seed oil).Results The extraction yield of sea buckthorn seeds pretreated by ultrafine grinding combined with flaking was 78.97%, significantly higher than that obtained by conventional grinding or ultrafine grinding alone. The optimal extraction parameters for subcritical butane were as follows: a solid-to-liquid ratio of 1∶10 (g/mL), extraction time of 64 min, and extraction temperature of 52 ℃. Under these conditions, the extraction yield of sea buckthorn seed oil was 95.21%, which was 5.54%, 3.21%, and 1.25% higher than that of C-sea buckthorn seed oil, E-sea buckthorn seed oil, and S-sea buckthorn seed oil, respectively. Y-sea buckthorn seed oil had the highest iodine value and the lowest saponification value. The main fatty acids in sea buckthorn seed oil were linoleic acid, α-linolenic acid, and palmitic acid. The vitamin E content of Y-sea buckthorn seed oil was 182.5 mg/100 g, with relatively high content of squalene and total sterols. It also had the highest total flavonoid and total phenol content, as well as the strongest DPPH radical scavenging rate, ABTS⁺ radical scavenging rate, and FRAP antioxidant capacity.Conclusion Sea buckthorn seed oil obtained by subcritical butane extraction possesses relatively stable physicochemical properties, high levels of nutritional and bioactive substances, and strong antioxidant capacity.