Due　to　the　long　service　period　and　irregularities　in　construction,　a　large　amount　of　existing　brick　masonry　structures　around　the　world　have　been　deteriorated　in　performance,　which　are　in　urgent　need　of　reinforcement　measures.　Ultra-high　performance　engineered　cementitious　composite　(UHPECC)　is　a　promising　material　to　the　rehabilitation　of　existing　brick　wall,　where,　the　mechanical　properties　of　interface　is　essential　to　the　reinforcement.　In　this　study,　the　bonding　behavior　of　interface　between　UHPECC　and　existing　brick　walls　was　investigated　by　double-sided　shear　test,　and　the　influence　of　joint　depth　on　shearing　performance　was　analyzed　by　experiment　and　numerical　simulation.　The　results　show　that　the　interfacial　shear　strength　between　UHPECC　and　existingbrick　wall　is　increased　with　the　increment　of　UHPECC　joint　depth.　The　shearing　load-displacement　curve　generally　includes　initial　stage,　elastic　stage　and　plastic　stage,　where,　the　specimen　H0　only　undergoes　an　elastic　stage,　H5　has　no　plastic　stage,　and　the　H15　and　H25　have　comparable　load　evolution　curves.　The　optimal　joint　depth　for　UHPECC　reinforced　brick　wall　is　15　mm.　The　established　model　is　reliable　to　simulate　the　interfacial　shear　performance　of　UHPECC　reinforced　brick　wall.　Due　to　the　redistribution,　the　shear　stress　is　mainly　concentrated　near　the　joint,　which　is　obvious　with　the　increasing　of　UHPECC　joint　depth.　Based　on　the　experimental　and　numerical　simulation,　a　relationship　of　interfacial　shear　strength　and　UHPECC　joint　depth　is　proposed.　©　2025　Elsevier　Ltd