Intense　2.9　mu　m　emission　corresponding　to　Dy3+:H-6(13/2)　-＞　H-6(15/2)　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　mu　m　emission,　but　also　has　longer　upper　laser　level　lifetime,　which　facilitates　particle　number　inversion　and　laser　behavior　in　2.9　mu　m.　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　mu　m　laser　in　Dy3+:CaYAlO4　crystal,　which　could　act　as　a　potential　gain　media　for　LD　pumped　mid-infrared　laser.