En-echelon　joints　occur　widely　in　rock　masses　and　are　often　subjected　to　dynamic　loads　during　earthquakes　and　rock　bursts,　which　considerably　influence　stability　in　rock　engineering.　However,　little　is　known　of　the　cyclic　shear　behavior　of　en-echelon　joints.　This　study　conducted　a　series　of　cyclic　shear　tests　on　en-echelon　joints　under　constant　normal　load　(CNL)　boundary　conditions　to　investigate　the　cyclic　shear　behavior　and　dilation　charac-teristics.　The　results　show　that　shearing　mechanisms　of　en-echelon　joints　were　determined　by　joint　angles　during　cyclic　shearing,　leading　to　differences　in　the　evolution　of　shear　resistance　and　dilation　characteristics.　A　new　phenomenon　was　observed,　in　that,　shear　stresses　increased　and　decreased　with　an　increase　in　the　number　of　cycles　during　small　and　large　shear　displacements,　respectively.　The　shear　strengths　and　average　dilation　angles　under　cyclic　shear　loads　decreased　with　increasing　number　of　cycles.　The　difference　in　the　peak　shear　stresses　between　en-echelon　joints　with　different　joint　angles　decreased　with　the　number　of　cycles　(N).　Finally,　dilation　only　occurred　in　the　first　several　cycles,　contraction　predominated　after　several　cycles,　and　the　contraction　of　the　specimens　at　a　positive　angle　was　larger　than　that　at　a　negative　angle.　These　findings　hold　crucial　implications　for　predicting　surface　ruptures　after　earthquakes.