The invention discloses a medical vertebral arch pedicle renovating screw assembly which comprises a screw sheath and a screw which are mutually matched, wherein the screw sheath has certain mechanical strength and toughness, and the medical absorbable material can effectively maintain the mechanical strength for 2 to 3 months in vivo; the screw sheath is divided into a head end and a sheath body;the head end is a cone with a sealed front end, and the sheath body is a cylinder; external threads are arranged on the outer surface of the cylinder, and a longitudinally extended triangular prism-shaped cavity is arranged in the cylinder; the cylinder is divided into three side walls by the cavity, and internal threads are designed on the inner wall of the cavity; the screw is made of medical titanium alloy and comprises a thread section and a tail part; the thread section is formed by connecting a screw tip and a screw body, and both the screw tip and the screw body are in external threaddesign; the tail part is provided with a radially communicated U-shaped groove, and internal threads are arranged on the inner wall of the U-shaped groove. The invention can improve the internal fixation stability and reliability of the spinal column in a renovating operation or the secondary screw arranging process, reduce the occurring rate of vertebral arch pedicle screw loosening and even separation and lower the failure rate of operations.