This　study　investigates　the　elfects　of　the　steel-UHPC　composite　pavement　on　the　long-term　Performance　of　orthotropic　steel　deck　and　the　degradation　mechanism　of　the　steel-UHPC　composite　pavement.　Based　on　an　existing　bridge　that　has　been　retrofitted　by　a　steel-UHPC　composite　pavement,　the　long-term　Performance　of　the　composite　pavement　as　well　as　the　strength　of　shear　studs　were　examined.　The　data　concerning　the　appearance　deterioration　and　cracks　in　steel　deck　plates　over　ten　years,　together　with　the　data　obtained　by　load　tests,　were　utilized　to　analyze　the　long-term　Performance　and　degradation　mechanism　of　the　steel-UHPC　composite　pavement.　In-house　and　field　tests　were　conducted　to　examine　the　strength　of　shear　studs,　based　on　which　the　relationship　between　loads　and　slip　of　the　shear　studs　at　the　Service　stage　was　investigated.　Two　approaches　were　applied　to　calculate　the　strength　of　shear　studs　before　Service　and　at　Service　stage.　It　is　concluded　that　the　steel-UHPC　composite　deck　pavement　can　stably　suppress　the　fatiguc　Cracking　of　the　orthotropic　steel　deck　plate　and　prevent　early　occurrence　of　ruts　in　the　asphalt　wcaring　layer,　and　stably　improve　the　stress　distribution　and　local　stiffness　of　the　bridge　deck.　After　serving　for　10　years,　the　local　stiffness　of　deck　nearing　girder　end　has　dropped　to　62.　8%　of　the　initial　stiffness.　The　degradation　of　the　clastic　stiffness　of　shear　studs　is　a　key　indicator　of　significant　reduetion　of　local　stiffness　of　the　steel-UHPC　composite　pavement.　Due　to　that　the　Performance　of　shear　studs　is　closely　related　to　the　covering　UHPC,　it　is　critical　to　control　the　compaction　of　the　UHPC　at　the　intersections　of　rcinforcement　during　the　placement　of　UHPC.　©　2025　Wuhan　Bridge　Media　Co.,　Ltd.,　MBEC.　All　rights　reserved.