Dravet syndrome is a rare and severe epileptic encephalopathy that begins in infancy. Over 80% of patients have mutations in the SCN1A gene, and they can also experience seizures triggered by various external factors such as heat, visual stimulation, infection and environmental pollutants. Among these environmental pollutants, there is increasing social interest in microplastics (MPs), which are known to accumulate in organs and pose a threat to health, but their association with brain diseases is not well understood. In this study, we investigating the effects of MPs exposure on seizures and neurotoxicity in SCN1A^+/- ​cerebral organoids and mouse models. We found that MPs infiltrated into cerebral organoids and mouse brain, leading to alterations in the expression of inflammation- and neurotoxicity-related markers. Interestingly, when exposed to MPs in SCN1A^+/-​ mice, the induction time of each seizure stage was accelerated compared to the wild-type mice, and seizures were induced at relatively lower temperatures. These results demonstrate that exposure to MPs can be very fatal for patients with Dravet syndrome and can increase understanding of the relationship between the increase in MPs in the environment and neurological diseases.