Objective To optimize the extraction process of astaxanthin from Haematococcus pluvialis with deep eutectic solvent (DES) and evaluate the antioxidant activity of the extracted astaxanthin.Methods The choline chloride-ethylene glycol system is employed to optimize the astaxanthin extraction process from H. pluvialis through single-factor experiments and response surface methodology, with extraction rate as the key indicator. The DPPH and hydroxyl radical scavenging activities of astaxanthin are determined, followed by assessment of preservation effects on fresh-cut apples.Results The optimal process parameters for the extraction of astaxanthin from H. pluvialis by choline chloride-ethylene glycol are determined as follows: solvent water content of 10%, extraction temperature of 45 ℃, extraction time of 99 min, and solid-to-liquid ratio of 1:16 (g/mL). Under these conditions, the extraction rate of astaxanthin is 38.64 mg/g. The DPPH and hydroxyl free radical scavenging rates of astaxanthin extract (40 μmol/L) prepared by this method are 39.04% and 90.15%, respectively. Astaxanthin can effectively delay the weight loss rate of fresh-cut apples, and 25 mg/mL astaxanthin extract decreases the malondialdehyde content by as high as 53.88%.Conclusion It is feasible to isolate astaxanthin from H. pluvialis based on the DES method. The astaxanthin extracted by this method has strong antioxidant activity and a certain preservation effect on fresh-cut apples.