Abstract: The investigated thin-walled slender shaft exhibits complex characteristics, featuring a large depth-to-diameter ratio, variable cross-section and non-uniform thin walls, possessing challenges in forming. Utilizing DEFORM-3D software,hot extrusion simulation of 6061 aluminum alloy was conducted, evaluating the forming outcomes of thin-walled slender shafts based on deformation uniformity and damage values. Orthogonal experiments were employed to scrutinize the impact of forming process parameters on the forming indices, and the deformation uniformity and damage values were optimized through gray correlation analysis. The dynamic recrystallization model of 6061 aluminum alloy was applied to explore the evolution of dynamic recrystallization under optimal extrusion process parameters. The results indicate that the billet temperature has a negligible effect on the extrusion forming,whereas extrusion sp eed significantly influences the extrusion forming of thin-walle d slender shafts within the selected process level interval. Grey correlation degree analysis facilitates multi-objective optimization, identifying the theoretical optimum process level when the extrusion speed is 10 mm/s, while the extrusion temperature can be selected from three levels. Consequently, an extrusion speed of 10 mm/s and an extrusion temperature of 400 ℃ are chosen as the optimal process levels. Under these parameters, the dynamic recrystallization occur s in both the inner and outer walls of the shaft during the extrusion process, leading to refined grains.