The invention discloses a steel reinforcement cage forming mechanism. The mechanism comprises a worktable, a fixed base and a sliding base are arranged on the worktable in a right facing manner, the fixed base and the worktable are fixedly connected, the sliding base and the worktable are in sliding fit, at least two stirrup forming devices are arranged on the fixed base, stirrup forming auxiliarydevices corresponding to the stirrup forming devices are arranged on the sliding base, the stirrup forming devices and the stirrup forming auxiliary devices are arranged on the fixed base and the sliding base in a sliding manner correspondingly, and a steel reinforcement cage preparing area is arranged between the stirrup forming device and the stirrup forming auxiliary device. Compared with theprior art, the steel reinforcement cage forming mechanism has the beneficial effects that operation is convenient, quality of the steel reinforcement cage can be effectively ensured, according to needs, the number of stirrups can be arranged, the strength of the steel reinforcement cage can be improved, the rotating precision of a stirrup ring is improved, the diameter need of the steel reinforcement cage is ensured, the output rotating speed is changed, the conveying speed of reinforcing steel bars is improved, machining of various specifications of the steel reinforcement cages can be achieved, production efficiency is high, and machining cost is low.