Ti∶sapphire crystal is a widely-used working material for ultra-short and ultra-intense laser oscillator. Its aperture and surface full-spatial-frequency wavefront errors determine the output energy and beam quality of ultra-short and ultra-intense laser system. However, owing to the extreme difficulty in obtaining good optical homogeneity and high Mohr hardness in the Ti∶sapphire crystal, it remains a great challenge to fabricate a large-aperture Ti∶sapphire with a high-precision transmission wavefront and super-smooth surface. High-precision transmission-wavefront measurements of the Ti∶sapphire crystal are realized through the design of a linear polarization interference detection method to match the crystal axis, which solves the problem that the interference fringes of transmission-wavefront measurements cannot usually be resolved owing to the birefringence caused by the structural characteristics of the Ti∶sapphire crystal. Based on the measurements and analysis on the optical homogeneity of the Ti∶sapphire crystal, a fast polishing convergence process for the transmission wavefront is developed using an uniaxial machine. In order to realize the process for transmission wavefront with high accuracy and low frequency error and the process for super-smooth surface with high frequency error, orthogonal experiments combined with the grey relational analysis method are used to optimize the processing parameters of a computer-controlled small-grinding-head polishing. A small-grinding-head smoothing process using silica sol polishing fluid is developed to reduce the mid-spatial-frequency errors. Experimental results show that the transmission-wavefront errors of the large-aperture Ti∶sapphire crystal at full spatial frequency can be effectively controlled by using multi-way processing technologies. For a large-aperture Ti∶sapphire crystal with a diameter of 120 mm, the peak-valley value of the transmission wavefront can reach 0.283λ (λ=632.8 nm), the power spectral density of intermediate frequency shows that there is no obvious error modulation at special frequency. A super-smooth surface is realized with a high-frequency roughness Rq of approximately 0.262 nm.