Abstract: Objective: This study aimed to determine optimal extraction conditions for polyphenols from a carrot preserve and analyze their composition, compositional changes, and antioxidant activity. Methods: Fresh carrots were used as raw materials and processed into carrot preserve through a variable temperature fermentation process. Polyphenol extraction from the preserve was optimized through response surface methodology. Polyphenol content and changes due to processing were analyzed with liquid chromatography tandem-mass spectrometry (LC-MS/MS). Antioxidant activity was assessed using in vitro models including 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) radical, 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid), diammonium salt radical cation (ABTS⁺·), 2-phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl 3-oxide (PTIO), hydroxyl radical (·OH), and a phosphomolybdenum assay for total antioxidant capacity. Results: The optimized extraction parameters for polyphenols were determined to be: a 74% ethanol concentration, a liquid-to-material ratio of 45:1 (mL/g), an extraction temperature of 72 °C, and an extraction time of 32 min. Under these conditions, a polyphenol yield of 5.57±0.13 mg GAE/g DW was obtained, representing an increase of approximately 518.89% in total phenol content compared to that in fresh carrots. Thirteen polyphenol monomers were identified in the carrot preserve, with ferulic acid, caffeic acid, and quercetin being found to be the most abundant at 3116.85±146.26, 385.36±26.16, and 314.76±7.70 μg/g, respectively. Effective scavenging of DPPH·, ABTS⁺·, PTIO·, and hydroxyl radicals was demonstrated by both carrot preserve and fresh carrot polyphenols, with respective IC₅₀ values of 4.324, 11.64, 25.37, and 20.54 mg/mL being recorded for carrot preserve, and 17.55, 22.53, 107.6, and 39.54 mg/mL for fresh carrots. A positive correlation was observed between scavenging ability and polyphenol concentration. Regarding total antioxidant capacity, significantly higher capacity was exhibited by polyphenols in carrot preserve than by those in fresh carrot polyphenols (P<0.01). Conclusion: Response surface methodology was applied to optimize the extraction process of polyphenols from carrot preserve. The total phenol content of carrot preserve produced from fresh carrots through variable temperature fermentation was significantly increased, and the polyphenols, including ferulic acid, caffeic acid, and other hydroxycinnamic acid derivatives, were observed to exhibit a notable increase in antioxidant activity. These findings were considered to lay a foundation for further research and development of carrot preserve and were regarded as providing valuable insights for advancing the deep processing of carrots.