The　peak　shear　displacement　(PSD)　of　artificial　joints　was　studied　by　the　shear　test　of　cement　mortar　duplicate　joints　under　constant　normal　load.　First,　the　splitting　rock　joints　were　produced　by　the　Brazilian　splitting　method,　and　the　high-precision　point　cloud　of　joint　surface　morphology　was　acquired　by　three-dimensional　(3D)　scanning　method.　The　polylactic　acid　(PLA)　base　mold　was　produced　by　3D　printing　technology.　The　duplicate　joints　with　the　same　joint　surface　as　the　splitting　rock　joints　were　obtained　by　pouring　cement　mortar　on　the　PLA　base　mold.　Then,　shear　tests　of　20　cement　mortar　specimens　with　5　groups　of　joint　surface　morphologies　under　4　different　normal　loads　were　carried　out,　and　the　joint　shear　stress-displacement　curves　were　obtained.　The　influencing　factors　of　the　PSD　were　studied.　The　results　indicate　that　the　PSD　is　inversely　related　to　the　joint　roughness　and　positively　related　to　the　normal　stress　(NS).　The　limitation　of　Barton＇s　empirical　formula　is　that　it　cannot　predict　(fit)　the　PSD　of　the　joints　with　JRC　=　0　and　reflect　the　effect　of　NS　on　the　PSD.　To　quantitatively　study　the　PSD　of　joints,　an　empirical　formula　that　can　comprehensively　consider　the　influence　of　surface　roughness　and　NS　is　introduced　based　on　the　test　results.　The　modified　model　overcomes　the　limitation　of　Barton＇s　empirical　formula　which　ignored　the　NS　and　can　well　reflect　the　sensitivity　of　joint　roughness　coefficient　(JRC)　to　PSD.　The　acquisition　of　PSD　can　provide　a　basis　for　the　numerical　simulation　of　rock　engineering　and　provide　quantitative　research　methods　for　the　analysis　of　stick-slip　events.