With　the　help　of　3D　printing　and　3D　laser　scanning　techniques,　cement　mortar　joint　samples　with　a　certain　surface　morphology　were　prepared.　Shear　tests　of　20　sets　of　matching　joint　samples　and　8　sets　of　joint　samples　with　different　percentages　of　cavity　area　were　performed　under　constant　normal　load　and　uniform　shear　displacement.　The　results　show　that　the　distribution　characteristics　of　the　equivalent　height　difference　based　on　the　new　roughness　description　were　in　accordance　with　the　distribution　of　the　wearing　area　after　shearing,　and　the　effect　of　cavities　on　the　peak　shear　strength　is　essentially　due　to　the　influence　of　the　cavities　on　the　roughness　of　the　joint　surface.　The　relationships　between　the　peak　shear　strength　and　the　two　roughness　parameters　were　discussed,　and　a　new　criterion　for　predicting　the　peak　shear　strength　of　rock　joints　was　proposed.　It　was　noted　that　the　roughness　parameter　system　adopted　in　this　paper,　which　can　describe　the　peak　shear　strength,　was　reasonable.　The　roughness　anisotropy　of　the　five　joint　surfaces　was　discussed,　and　a　corresponding　quantification　parameter　A(AHD)　accounting　for　the　roughness　anisotropy　was　proposed.　The　roughness　of　the　joint　surface　has　a　positive　size　effect,　a　negative　size　effect　and　no　size　effect　in　a　certain　direction.　However,　no　matter　the　direction,　the　roughness　parameters　will　gradually　stabilize　as　the　research　scale　increases.　A　similar　relationship　between　the　roughness　anisotropy　parameters　and　research　scales　was　also　observed.　To　check　the　applicability　of　the　proposed　criterion　for　estimating　the　peak　shear　strength　of　natural　rock　joints,　12　sets　of　rock　joints　with　the　same　surface　morphology　were　produced　based　on　a　numerically　controlled　engraving　technique.　Under　the　same　loading　conditions　as　those　in　the　shear　tests　of　the　cement　mortar　replication　joints,　the　peak　shear　strengths　of　the　rock　joints　were　tested,　and　the　results　indicated　that　the　new　criterion　was　also　applicable　to　predict　the　peak　shear　strength　of　natural　rock　joints.