Intense　2.9　µm　emission　corresponding　to　Dy3+:6H13/2　→　6H15/2　transition　was　achieved　in　Yb3+/Dy3+　codoped　CaYAlO4　crystal　for　the　first　time.　The　effects　of　Yb3+　on　the　spectroscopic　properties　and　energy　transfer　mechanisms　were　investigated.　In　comparison　with　Dy3+　singly-doped　CaYAlO4　crystal,　Yb3+/Dy3+　codoped　crystal　not　only　has　intense　2.9　µm　emission,　but　also　has　longer　upper　laser　level　lifetime,　which　facilitates　particle　number　inversion　and　laser　behavior　in　2.9　µm.　Furthermore,　the　energy　transfer　efficiency　from　Yb3+　to　Dy3+　in　Yb3+/Dy3+　codoped　crystal　was　as　high　as　87.3%,　indicating　effective　energy　transfer　of　Yb3+.　Besides,　the　energy　transfer　microscopic　parameters　between　Yb3+　and　Dy3+　were　theoretically　analyzed.　The　results　indicate　that　the　introduction　of　Yb3+　is　very　beneficial　for　achieving　2.9　µm　laser　in　Dy3+:　CaYAlO4　crystal,　which　could　act　as　a　potential　gain　media　for　LD　pumped　mid-infrared　laser.　©　2018　Elsevier　B.V.