Abstract: Submerged plants are important primary producers that play vital roles in aquatic ecosystems, yet their populations are increasingly threatened by water pollution. Among emerging pollutants, silver nanoparticles (AgNPs), widely used in industrial and consumer products, pose a growing ecological risk due to their release into freshwater systems. However, the physiological and developmental responses of submerged plants to AgNPs are still poorly understood. This study systematically examined the effects of AgNP pollution on the submerged plant Potamogeton crispus, focusing on turion germination, seedling growth, photosynthetic performance, and oxidative stress responses. Results showed that exposure to AgNPs at concentrations between 0.25 and 1 mg/L markedly suppressed turion germination and inhibited seedling growth. Elemental analysis confirmed significant Ag accumulation in both shoots and roots of seedlings. Chlorophyll a, chlorophyll b, and carotenoid levels decreased significantly under 0.50 and 1 mg/L AgNP treatments. F_v/F_m did not show significant differences under all treatments of AgNPs, but Y(Ⅱ), rETR_max, and qP were significantly reduced at AgNPs concentrations higher than 0.50 mg/L. Concurrently, elevated activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), along with increased malondialdehyde (MDA) content, were detected following AgNP treatment. Collectively, these findings demonstrate that AgNPs significantly disrupt both growth and physiological integrity in P. crispus, highlighting the vulnerability of submerged macrophytes to nanoparticle contamination. This study provides an important theoretical basis for understanding the phytotoxic mechanisms and aquatic toxicological effects of AgNPs on submerged plants and for evaluating the ecological and environmental safety of AgNPs in freshwater environments.