Abstract: A predefined-time adaptive fuzzy attitude quantization control algorithm is proposed for spacecraft system in the presence of inertia uncertainties, external disturbances and input quantization. During the process of the controller design, a fuzzy logic system is used to approximate the nonlinear item of the system, and a hysteresis quantizer is introduced to mitigate chattering issues in the quantization signal. On this basis, a predefined-time adaptive fuzzy attitude controller is designed to ensure that the spacecraft attitude can converge into neighborhood near the origin point within a predefined time, which can be explicitly determined in advance by adjusting a simple parameter. Compared with the existing predefined-time control algorithms, the singularity problem of the proposed algorithm can be avoided directly without requiring the input of any piecewise continuous functions or quadratic fractional functions, making the stability analysis more concise. Finally, the effectiveness of the proposed algorithm is validated by the simulation results.