Abstract: As a new type of pollutant, microplastics have attracted serious concern and extensive research worldwide. To gain insights into the characteristics of microplastic pollution in sediments in Shiwuli River, microplastics were detected by optical microscope, and the composition and surface morphology of microplastics were analyzed by Fourier Infrared Spectrometer, Scanning Electron Microscope, and Energy Dispersive Spectroscopy. The results showed that the pollution degree of microplastics in the sediments was below the medium level. From the upper to lower reach, the abundance of microplastics in sediments decreased first and then increased. The microplastics in the upper and middle reach sediments were mainly fragments and fiber shapes, and accounted for 85 % and 87 % of total microplastics in 0.5~3 mm size, respectively. However, in sediments in the lower reach, fragments and films were the main proportion shapes. Microplastics in 0~0.5 mm and 0.5~3 mm size accounted for 56 % and 43 % of total microplastics, respectively. The main microplastic components were polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE) and polystyrene (PS). PET was the most proportion of the four components in sediment microplastics from the upper and middle river reaches. These four components were shown to be more uniform in sediment microplastics in the lower river reach. The surface of sediment microplastic was rough, porous and convex, and Si, Fe, Ca, Al etc. were detected on the microplastic surface. Moreover, the fibrous microplastic surface showed the most serious breakage and diverse morphology, and more types of metal elements were detected on the fibrous microplastic surface. The abundance, morphology, particle size and components of microplastics in sediments in different river reaches basically reflected the hydrological conditions and pollution sources in different river reaches. These results provided basic data and scientific reference for the prevention and control of microplastics pollution in Shiwuli River.