With　rapid　urbanization,　the　negative　external　effects　of　urban　agriculture　have　been　gradually　highlighted.　A　quantitative　description　of　environmental　loss　is　the　precondition　of　environmental　pollution　control.　Meanwhile,　the　scenario　analysis　settings　based　on　model　simulation　and　different　control　schemes　have　guiding　significance　for　mitigating　the　current　status　of　agricultural　non-point　source　pollution　(ANSP).　In　this　study,　we　choose　the　Jinjiang　River　basin　as　the　study　area,　and　the　denitrification　decomposition　(DNDC)　model　was　used　to　simulate　the　nitrogen　cycle　in　the　paddy　ecosystem　and　the　revised　universal　soil　loss　equation　(RUSLE)　model　was　used　with　a　nitrogen　pollution　load　to　construct　the　framework　of　risk　assessment　in　agricultural　nonpoint　source　pollution　in　ANSP.　In　addition,　the　best　management　practice　(BMP)　of　agricultural　nonpoint　source　pollution　control　was　discussed.　Our　results　are　as　follows:　(1)　The　average　annual　soil　erosion　is　3161　t/km2,　which　equates　to　moderate　erosion.　The　average　value　of　the　nitrogen　pollution　load　is　0.33　t/hm2,　and　the　total　nitrogen　loss　load　in　the　catchment　is　1.66　×　105　t/a.　High-level　risks　are　distributed　on　both　sides　of　the　river　system.　(2)　Based　on　the　scenario　simulation　of　continuous　cropping　using　traditional　management　practices　(TMPs),　the　average　loss　of　nitrogen　leaching　in　2030　is　67.74%　higher　than　in　2017.　(3)　A　comprehensive　BMP　with　regional　differences　is　proposed.　Under　the　premise　of　guaranteeing　the　amount　of　nitrogen　absorbed　by　crops,　this　scheme　can　reduce　the　nitrogen　loss　by　about　40.72%　in　2030.　The　current　status　of　ANSP　cannot　be　underestimated.　Reasonable　and　differentiated　measures　to　improve　agricultural　management　can　effectively　alleviate　the　risks　of　nitrogen　leaching　from　farmland.　©　2020,　©　2020　Taylor　&　Francis　Group,　LLC.