The controlling microplastics (MPs) at source is a management method that can effectively reduce the amount of contamination in the environment. The main source of MPs was landfills that the decomposition of solid waste, MPs has an impact on environmental quality especially the health of humans. This research was investigated of MPs contamination at landfill site in the Muangpak municipality for analysis of MPs quantitative and source apportionment of MPs. The results of the composition of municipal solid waste by quartering method found that biodegradable solid waste was as high as 36.27% followed by general solid waste of 35.97% which was mostly plastic waste and effect the contamination of MPs in the environment. The distribution of MPs in environmental found that highest abundance was 66.44% of leachate sludge pond 1 followed by leachate sludge pond 2 (26.30%), sediment of surface water (3.32%), leachate pond 1 (1.04%), leachate pond 2 (0.80%), groundwater point 3 (0.62%), groundwater point 1 (0.58%), surface water (0.53%) and groundwater point 2 (0.37%). The contamination of polymer types of MPs at higher densities of low density polyethylene (LDPE) and high density polyethylene (HDPE) than polypropylene (PP) was found in samples closest to landfill area especially leachate pond more than 90%. The source apportionment of MPs using statistical analysis found that plastic waste has correlated to occurrence of LDPE and plastic bottle waste has correlated to occurrence of HDPE that both types of plastic waste are related to the amount of general solid waste and recycle solid waste increases every year.