The aim of this study was to investigate three kinds of different antifreeze agents on quality and nutrition of Litopenaeus vannamei during freezing and thawing (F-T) cycles. Fresh samples were immersed in 30 g/L sucrose sorbitol (SS), 30 g/L sodium tripolyphosphate (ST) and 30 g/L carrageenan oligosaccharides (CO) solutions for 2 h, respectively, with samples immersed in sterile water for 2 h as the control group (CK). Treated samples were packed in PE bags in frozen storage, and 6 cycles of the repeated freezing and thawing were simulated. The anti-freezing effects of different antifreeze agents were evaluated by water holding capability (WHC), Ca²⁺-ATPase activity, magnetic resonance imaging (MRI) and Fourier transform infrared imaging (FT-IRI). The nutritional value changes of Pacific white shrimp during F-T cycles were analyzed by the contents of basic nutrional ingredients and amino acids. The results showed that compared with SS and ST samples, the treatment of carrageenan oligosaccharides could effectively inhibit the decrease of WHC, Ca^{2 +}-ATPase activities and basic nutrional ingredients of freeze-thaw samples; According to amino acid analysis, the content of umami amino acids, essential amino acids and total amino acids in CO treated samples were all kept at a high level during F-T periods; MRI and FT-IRI could reflect the changes of protein content and water migration in shrimp directly. In conclusion, the protective effects of carrageenan oligosaccharides on protein, lipid and water of shrimp were significant. It could not only play an important role in water retention and cryoprotective effects, but also keep the better quality and nutrition of Litopenaeus vannamei.