Recently, the transgenerational toxicity of nanoplastics has received increasing attention.Caenorhabditis elegansis a useful model to assess the transgenerational toxicity of different pollutants. In nematodes, the possibility of early-life exposure to sulfonate-modified polystyrene nanoparticle (PS-S NP) causing transgenerational toxicity and its underlying mechanisms were investigated. After exposure at the L1-larval stage, transgenerational inhibition in both locomotion behavior (body bend and head thrash) and reproductive capacity (number of offspring and fertilized egg number in uterus) was induced by 1–100 μg/L PS-S NP. Meanwhile, after exposure to 1–100 μg/L PS-S NP, the expression of germlinelag-2encoding Notch ligand was increased not only at the parental generation (P0-G) but also in the offspring, and the transgenerational toxicity was inhibited by the germline RNA interference (RNAi) oflag-2. During the transgenerational toxicity formation, the parental LAG-2 activated the corresponding Notch receptor GLP-1 in the offspring, and transgenerational toxicity was also suppressed byglp-1RNAi. GLP-1 functioned in the germline and the neurons to mediate the PS-S NP toxicity. In PS-S NP-exposed nematodes, germline GLP-1 activated the insulin peptides of INS-39, INS-3, and DAF-28, and neuronal GLP-1 inhibited the DAF-7, DBL-1, and GLB-10. Therefore, the exposure risk in inducing transgenerational toxicity through PS-S NP was suggested, and this transgenerational toxicity was mediated by the activation of germline Notch signal in organisms.