Abstract: In view of the low strength and brittleness of coal gangue slag geopolymer (CGS), carbon fiber (CF) was introduced to improve the performance of CGS for efficient utilization. The geopolymer was prepared using ball-milled coal gangue and ground granulated blast furnace slag (GGBS) as precursors with sodium silicate as the activator. Two curing conditions: Standard curing and 60℃ curing, were applied to explore the effects of different CF volume fractions on the compressive and flexural strength, fracture toughness, rheological behavior, pore structure and drying shrinkage of CGS. The results showed that CF content significantly improved the overall performance of CGS. At the CF content of 0.6%, the 28-d compressive strength under standard curing and 60℃ curing reached 17.00 MPa and 24.80 MPa, respectively, improving by 28.30% and 44.19% compared to the reference group. The crack initiation toughness and instability toughness increased by 64.88%/47.91% (standard/60℃ curing) and 66.75%/48.11% (standard/60℃ curing), respectively. Rheological analysis revealed that CF reduced flowability, but improved thixotropy, yield stress, and plastic viscosity. The 3D network structure of 1.0% CF decreased the 28-day drying shrinkage by 23.98% (standard curing) and 40.56% (60℃ curing) relative to the control. The micro analysis shows that CF is closely combined with the matrix, and the appropriate introduction can optimize the pore structure, and reduce the porosity and improve the compactness of the matrix.