The work aims to optimize the design of walking aids for preschool children with cerebral palsy, in order to reduce the potential safety hazards of walking aids for preschool children with cerebral palsy, solve the problem of secondary injury of limbs in the training process and improve the comfort of walking aids. Through the analysis by the RULA tool of the JACK virtual simulation software, the unreasonable postures of preschool children with cerebral palsy in the process of using the walking aids were obtained, the ergonomics and force were analyzed, the improvement methods were proposed and the design was optimized, and finally the JACK virtual simulation software was imported to verify the risk and comfort. After optimization, the injury risk of preschool children with cerebral palsy using walking aids was reduced from grade 4 to grade 1, the postural load index of the children's trunk bending force, L4/L5 spinal compression force, and shear force decreased by 53%, 47%, and 81% and each joint of the upper body was at a comfortable angle. After JACK simulation analysis and ergonomic optimization, the walking aids effectively reduce the risk of secondary injury in the rehabilitation training of preschool children with cerebral palsy, reduce the physical burden of children in walking training, and improve the using comfort.