In this study,the ultrasonic-assisted deep eutectic solvent (DES) method was utilized for the extraction of essential oil from Trichosanthes kirilowii seeds.A systematic investigation was conducted to study its chemical composition and antioxidant biological activities.Initially,the optimal ratio of DES was screened,followed by single-factor experiments to assess the effects of ultrasonic time,power,liquid-solid ratio,and distillation time on the yield of essential oil.Box-Behnken experimental design was employed to optimize the process parameters.GC-MS was applied to analyze the chemical composition of the essential oil.In vitro free radical scavenging experiments and biological assays including cell viability,cytokine levels and enzymatic activity in human epidermis cells were performed to evaluate its antioxidant property.The results demonstrated that a DES ratio of betaine∶glycerol = 4∶3 was suitable for extracting essential oil from T.kirilowii seeds.Response surface optimization yielded the optimal process conditions:an ultrasonic time of 33.6 min,power of 370 W,liquid-solid ratio of 7∶1(mL/g),and distillation time of 70 min.Under these conditions,the extraction rate of essential oil reached 9.24%.GC-MS analysis identified 13 principal volatile components (23.90%),including L-ascorbic acid 2,6-hexacosanedioate and cis-13,16-docosenoic acid,along with nine major fatty acid components (51.8%),such as palmitic acid and linoleic acid.In vitro antioxidant tests revealed that the essential oil exhibited higher efficiency in scavenging hydroxyl radicals compared to organic free radicals like DPPH and ABTS.Furthermore,cell experiments indicated that within the non-toxic concentration range (< 100 μg/mL),the essential oil significantly reduced the level of malondialdehyde (MDA) and maintained the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px),thereby effectively resist the oxidative stress damage induced by H₂O₂. This study provided a theoretical basis for the efficient extraction of essential oil from Trichosanthes kirilowii seeds and its application in natural antioxidant products.