Fluorescent　labeling　and　imaging　is　a　useful　tool　to　track　the　temporal　and　spatial　distribution　of　microplastics　(MPs)　with　size　and　shape　features.　However,　the　limited　fluorescently　labeled　MPs　spheres,　photo-bleaching　and　leaching　of　organic　small　molecular　dyes　hamper　the　tracking　of　MPs　in　the　environment.　In　this　work,　phenyl-modified　carbon　nitride　(PMCN)　fluorescent　polymer　was　prepared　and　applied　for　the　staining　of　eight　different　types　of　MPs.　The　interface　interaction　mechanism　between　PMCN　fluorescent　polymer　and　MPs　was　investigated　by　the　desorption　experiments.　The　long-time　photo-stability　of　the　stained　MPs　against　ultraviolet　(UV)　light　irradiation,　freeze-thaw　cycles,　various　environmental　factors　and　real　environmental　water　samples　was　evaluated.　The　MPs　stained　with　PMCN　fluorescent　polymer　showed　more　robust　stability　than　the　common　dye　(Nile　red)　against　the　damage　when　exposure　to　UV　light　for　72　h,　treatment　with　freeze-thaw　cycles　for　60　days,　exposure　to　strong　acid,　strong　alkali,　high　salinity,　freshwater　(river　and　lake)　or　seawater　for　60　days.　Results　indicate　PMCN　fluorescent　polymer　is　promising　as　a　convenient,　efficient　and　universal　fluorescent　tracer　for　visually　tracking　the　migration　and　distribution　of　MPs　in　environmental　water　system.　©　2024　The　Authors