Antibiotic　contamination　is　increasing　scrutinized　recently.　In　this　work,　the　Ag−AgCl/WO3/g-C3N4　(AWC)　nanocomposites　were　successfully　synthesized　using　a　two-step　process　involving　electrostatic　self-assembly　and　in-situ　deposition　for　trimethoprim　(TMP)　degradation.　The　as-prepared　photocatalysts　were　investigated　and　characterized　by　XRD,　FTIR,　XPS,　TGA,　SEM,　TEM,　UV–vis,　PL　and　EIS.　The　experimental　results　indicated　that　99.9%　of　TMP　(4　mg/L)　was　degraded　within　60　min　when　the　concentration　of　AWC　was　0.5　g/L.　Reactive　species　scavenging　experiments　and　electron　spin　resonance　(ESR)　experiments　illustrated　that　superoxide　radical　(•O2−)　and　photogenerated　holes　(h+)　were　the　main　active　species.　The　functional　theory　calculation　and　identification　of　intermediates　via　HPLC-MS　revealed　the　possible　degradation　pathways　of　TMP.　A　double　photoelectron-transfer　mechanism　in　AWC　photocatalyst　was　proposed.　Five　cycling　photocatalytic　tests　and　reactions　under　different　solution　matrix　effects　further　supported　that　the　AWC　was　a　promising　photocatalyst　for　the　removal　of　TMP　from　the　aquatic　environment.　©　2020　Elsevier　B.V.