Background: Polysaccharides are isolated from Rehmannia glutinosa (RG), a well-known traditional Chinese medicine starting from ancient China. However, their effects on anti-aging activity have not yet been evaluated. Objective: To evaluate the stress resistances and anti-aging effects of polysaccharides from RG by Caenorhabditis elegans N2 wild type. Materials and Methods: Preparing the polysaccharides from Rehmanniae radix preparata (PRRP) and Rehmanniae radix (PRR), we determined the antioxidant activity in vitro, stress resistance, lifespan, fertility, physical growth, locomotion, and impact on the formation of reactive oxygen species (ROS) on C. elegans. Results: The results showed that both polysaccharides have little scavenging ability of free radicals in vitro. After PRRP and PRR treatment, the stress resistance and body bending frequencies of nematodes were significantly increased. PRRP was shown to extend the lifespan and promote physical growth of C. elegans. Both polysaccharides had little effect on fertility and locomotion ability of C. elegans but can reduce excessive intracellular ROS. Conclusion: For C. elegans organism model, both PRRP and PRR are heat resistant and antioxidant; PRRP not only can extend lifespan but can also promote growth and development. PRRP had an anti-aging effect on C. elegans without affecting their reproductive capacity. Based on the scavenging capacity of ROS, we hypothesized that the mechanism of PRRP prolonging lifespan may be related to increase resistance and remove excess free radicals in time.