The invention discloses a vertebral arch pedicle extension device, which comprises a front nail, a core bar, a rear nail and a fixer. The core bar has a hollow structure, wherein the middle part of the core bar is provided with a through hole, the front end of the core bar is connected with the front nail by screw thread, the rear end of the core bar is sleeved with the rear nail, and the core bar is glidingly connected with the rear nail; the fixer is fixedly connected at the rear end of the rear nail and enables the core bar and the rear nail to be fixed oppositely. The vertebral arch pedicle extension device can separate a centrum from a vertebral arch pedicle and extend the distance therebetween, finally achieve the aims of expanding a vertebral canal and an intervertebral foramina and reducing pressure, can be applied to surgical operation on stenosis of the lumbar spine and has good application prospect.