Abstract: Microplastics are widely studied as emerging pollutants, but their distribution in the environmental media involved in the transmission path to the sea still needs further study. In order to provide more feasible basic data for the study of microplastic transport to the sea, this study sampled four environmental media (inlet waters, shore beach sediment, surface seawater and nearshore sediment) in Qinhuangdao sea during different water periods in 2019 and 2020, and the types, particle sizes, shapes and colors of microplastics were analyzed, and based on the above results, the distribution characteristics of microplastics in different environmental media along the transmission path to the sea were analyzed. The results show that microplastics pollution is widespread in Qinhuangdao sea area, and the overall level is moderate, the average abundance of microplastics in inlet waters, in shore beach sediment, in surface seawater and in nearshore sediment was (721.42±530.13) n/m³, (450.00±326.60) n/kg, (0.42±0.28) n/m³ and (613.24±410.04) n/kg. The comparison of results from different water periods showed that rainfall affects the microplastic content in the inlet waters, shore beach sediment and nearshore sediment; the spatial differences indicate showed that the distribution of microplastics was highly susceptible to the influence of human activities. In all types of environmental media, small particle size microplastics <0.5 mm account for a large proportion; microplastics with fibrous shape were more likely to be deposited in the aqueous environment, while fragmented and granular microplastics were more likely to be transported to the sediment environment; and the color of microplastics was not found to change significantly during the transmission. The types of microplastics found were mainly PET, Rayon, PE and PA and the analysis showed that the transport process also has an effect on the type distribution of microplastics.