The invention discloses YAG doped transparent ceramic, and a preparation method and application thereof. By adopting a solid-phase molding method and under the condition of vacuum high-temperature sintering, the high-transmissivity YAG doped transparent ceramic is obtained for the first time. The prepared YAG doped transparent ceramic has high-temperature stability and the optical property. In thepreparation process, a binder and a ball grinding solvent are adopted to be added into a mixed oxide of raw materials, meanwhile, low-valence-state sintering aids such as CaO and/or MgO are added, the sintering aids are used for stabilizing U<4+> and/or U<6+>, and Ca<2+> or Mg<2+> and high-valence-state doped U<4+> and/or U<6+> are used for stabilizing the position of to-be-replaced Y<3+>, then abiscuit is subjected to vacuum sintering, and the YAG doped transparent ceramic is obtained at the low temperature. When the CaO and/or the MgO serves as the sintering aid, the CaO and/or the MgO andsinter can form a solid solution, thus lattices distort to be activated to form a gap filling type solid solution or a vacancy type solid solution, the sintering temperature can be decreased, sintering is facilitated, and the high activity can be achieved.