CaSi₂O₂N₂:Ce³⁺/Eu²⁺ phosphors were successfully synthesized v ia the solid-state reaction method.Photoluminescence properties of Ce³⁺-doped,Eu²⁺-doped and Ce³⁺/Eu²⁺ codo ped samples are investigated.CaSi₂O₂N₂:Ce³⁺ phosphors show a broad band centered at 395nm under 333nm excitation.Red-shift occurs as the concen tration of Ce³⁺ increases.The molar quenching concentration of Ce³⁺ is approximately 1%.CaSi₂O₂N₂:Eu²⁺ phosphors emit a single,intense,and broad emission band centered at 540nm when excited at 397nm.The molar quenching concentration of Eu²⁺ is ap proximately 1%.When excited at 333nm,the codoped samples Ca0.99－2xSi₂O₂N₂:xCe³⁺,xLi⁺,0. 01Eu²⁺ emit two broad bands centered at 395nm and 540nm,respectively.The emission of Eu²⁺ is significantly enhanced by the increase of Ce³⁺ .When Ca0.98－ySi₂O₂N₂:0.01Ce³⁺,0.01Li⁺, yEu²⁺ phosphors are excited at 333nm,two broad bands with peaks at 395and 540nm are obse rved.The former band(at 395nm) is weakened when increasing Eu²⁺ content.However,the band at 540nm reaches the maximu m in tensity for y=0.004.These suggest effective energy transfer mechanism from Ce³⁺ to Eu²⁺ taking place in the CaSi ₂O₂N_2sample.The efficiency of energy transfer between Ce³⁺ and Eu 2+ is calculated,and saturation value occurs when the concentration of Eu 2+ increases to 1%.The resonance-type energy transfer between Ce³⁺ and E u²⁺ is dipole-dipole interaction mechanism.