Objective To study the anti-aging effects of kelp (Laminaria japonica) polysaccharides.Methods Polysaccharide is obtained from kelp by acid-assisted extraction methods. Based on the aging model of Caenorhabditis elegans, the animal's lipofuscin, reactive oxygen species (ROS), antioxidant capacity, and aging-related gene expression are analyzed to evaluate the effects of kelp polysaccharides on their life span, motility, and stress resistance.Results Compared with the control group, acid-extracted kelp polysaccharides (AKP) with different mass concentrations improve the life span, mobility, and stress resistance of C. elegans. Specifically, AKP significantly reduces the lipofuscin content and ROS levels, while increasing the activities of catalase and superoxide dismutase. In addition, kelp polysaccharides extend the life span of C. elegans by activating the expression of skn-1, daf-2, age-1, akt-1, and daf-16 mRNA, while up-regulating the expression of downstream factor mRNAs.Conclusion AKP can extend life span by increasing antioxidant capacity and regulating the insulin/insulin-like growth factor signaling pathway (IIS) of C. elegans.