To investigate the effects of nanoplastics (NPs) on rice seed priming and their underlying mechanisms, this study utilized four rice varieties (Wuyoudao 4, Yuxiangnuo 1, Yuxiangyou 8133, and Yongyou 4949) as experimental materials. Treatments included a blank control (CK) and NP treatments at concentrations of 0.1 mg/L (T1), 10 mg/L (T2), and 1000 mg/L (T3). Seed germination characteristics, seedling growth status, and antioxidant physiological indices (including activities of SOD, POD, CAT, and MDA content) were measured. The results showed that the T1 treatment slightly promoted seed germination, while the T2 and T3 treatments significantly inhibited it. All NPs treatments promoted shoot growth but inhibited root development, resulting in a decreased root-to-shoot ratio. The antioxidant enzyme responses exhibited an uncoupled phenomenon: SOD and CAT activities increased, POD activity was inhibited, and changes in MDA content varied depending on the variety and treatment concentration. Yongyou 4949 and Wuyoudao 4 exhibited strong tolerance with minimal oxidative damage, whereas Yuxiangnuo 1 and Yuxiangyou 8133 were more sensitive to NPs, showing aggravated membrane lipid peroxidation. This study provides a theoretical basis for stress-resistant rice cultivation, microplastic pollution prevention and control in farmland, and the selection of tolerant varieties, thereby contributing to the assurance of safe rice production.