Tantalum pentoxide and yttrium oxide were used as base materials. By adding alkali metal sintering agent Li₂CO₃, the doped tantalate ceramic samples were prepared by high temperature solid-phase sintering. The effects of alkali metal sintering agent Li₂CO₃ on the physical and chemical properties of rare earth yttrium tantalate coating were studied by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), laser pulse method (LFA), thermal-mechanical analyzer (TMA) and UV-visive-near-infrared spectrophotometer. The results show that under the sintering system at 1530℃, the ceramic is compact, resulting in Li₃TaO₄ ceramic. With more Li₂CO₃ inclusion, the higher Li₃TaO₄ of the second phase is generated. With a stable thermal expansion coefficient, the range of 8.2-8.6×10^-6K^-1(900℃); The Young's modulus and hardness of the samples decreased with the increase of the added sintering aid dose. When 6% alkali metal sintering agent Li₂O₃ is mixed into the ceramic, the transmittance rate of YTaO₄ ceramic can be stable at more than 80%, which shows that YTaO₄ ceramic has superior potential of optical ceramics.