The lithium tantalate crystal material is one of the perfect substrate materials for the manufacturing of surface acoustic wave (SAW) devices due to its good piezoelectric performance. In this paper, the geometry parameters of lithium tantalate wafer are controlled through researching the chemical etching process, lapping slurry particle size and mounting process. Finally, the lithium tantalate monocrystalline polished wafers with excellent geometry parameters are obtained. The TTV value of lithium tantalate wafer is less than equal to 5 μm, LTV value is less than or equal to 1.5 μm, the PLTV value of is great than or equal to 95%, Warp value is greater than or equal to 20 μm, Bow value is less than or equal to 10 μm. The quality level of lithium tantalate wafer has met the commercial requirements.