With　the　convenient　and　fast　requirements　for　construction　in　bridge　engineering,　prefabricated　assembly　technology　is　widely　applied　in　engineering　construction.　Typically,　prefabricated　bridge　decks　are　connected　through　cast-in-place　wet　joints.　Wet　joints,　as　the　primary　load-bearing　parts　of　bridge　decks,　undergo　complex　stress　and　are　prone　to　cracking　and　damage.　Particularly　in　the　negative　bending　moment　region　of　bridges,　the　influence　of　tensile　stress　on　wet　joints　is　more　severe,　thus　enhancing　the　mechanical　performance　and　crack　resistance　of　joints　becomes　crucial.　This　paper　investigates　the　mechanical　behavior　of　prefabricated　reinforced　concrete　bridge　deck　panels　with　variable　cross-sections　under　negative　bending　moments,　focusing　on　the　performance　of　Ultra　High-Performance　Concrete　(UHPC)　wet　joints.　Full-scale　experimental　tests　were　conducted　on　a　176　m　steel　truss　composite　continuous　rigid　bridge,　employing　C50　concrete　panels　with　UHPC　wet　joints.　Results　show　three　distinct　stages:　elastic,　crack　initiation　and　propagation,　and　failure.　The　maximum　failure　load　reached　822　kN,　with　a　maximum　displacement　of　21.64　mm.　Concrete　strains　indicate　compressive　stress　near　the　wet　joint　and　tensile　stress　near　the　loading　positions.　Cracks　primarily　develop　at　the　wet　joint　interface　and　propagate　under　increasing　load,　ultimately　leading　to　flexural-shear　failure　near　the　variable　cross-section　of　the　wet　joint.　Numerical　simulations　using　ABAQUS/CAE　(2020)　corroborate　experimental　findings,　closely　matching　load-displacement　curves　and　identifying　damage　locations.　The　study　demonstrates　that　UHPC　wet　joints　significantly　enhance　crack　resistance,　meeting　design　requirements　for　improved　mechanical　performance　in　bridge　structures　subjected　to　negative　bending　moments.