Yb:YAG transparent ceramics with high optical quality were fabricated by solid-state reaction and vacuum sintering method (1750 ℃×30 h) using high-purity Y₂O₃, α-Al₂O₃ and Yb₂O₃ powders as raw materials. The measured concentration of Yb ³⁺in 5.0at% Yb:YAG ceramics is 6.41×10 ²⁰ cm ^-3, and the cell density is 4.65 g/cm ³. The microstructures, spectral characteristics and laser performance parameters of Yb:YAG ceramics were studied in this work. FESEM results show that Yb:YAG ceramics have uniform and compact structure, clean and straight grain boundaries, and the average grain size is about (19±3) μm. The in-line transmittance of Yb:YAG ceramics with thickness of 4.0 mm reaches 82.5% at 400 nm and 85.2% at 1100 nm. The minimum pump saturation light intensity occurs at 940 nm, and the pump threshold power at 1030 nm is the lowest. The quality factor of 1030 nm laser pumped at 940 nm is 1.02×10 ^-22 cm·s. By calculating the gain cross section, it is indicated that Yb:YAG ceramics can be tuned broadband, and are ideal laser gain media.