Investigating　the　heterogeneous　distribution　pattern　of　plastic　pollution　in　river　systems　is　useful　for　better　understanding　the　transport　pathways　of　plastics　from　land　to　sea.　Therefore,　we　analyzed　samples　from　17　sites　to　evaluate　the　distribution　pattern　of　microplastics　(MPs)　in　Minjiang　River　Watershed.　The　MP　concentrations　ranged　between　0.12　and　2.72　n/L,　with　higher　microplastic　concentrations　located　in　urban　areas　with　greater　population　and　gross　domestic　product　(GDP)　densities.　MP　concentrations　were　positively　correlated　with　population　density,　GDP　density,　and　built-up　land　use　percentage,　suggesting　that　increasing　urbanization　level　will　lead　to　greater　plastic　pollution.　MP　concentrations　spanning　the　upstream　and　downstream　sides　of　the　SK　Hydropower　Dam　showed　decreasing　trends,　suggesting　that　MP　settling　would　occur　behind　the　dam　and　Shuikou　Reservoir　might　serve　as　a　sink　for　MPs.　This　study　provides　useful　insight　for　revealing　the　effects　of　urbanization　and　dams　on　spatial　distribution　of　riverine　MPs.