Objective: To evaluate the biomechanical properities of Pectin/ PVA composite(CoPP) hydrogel prosthetic nucleus，and provide scientific data for its clinical application. Methods: L4/5 functional spinal units from six fresh cadavers were used in the test. Under three different conditions (intact,  nucleotomy and  implantation of the prosthetic nucleus), the range of motion, netrol zone and intervertebral disc height were analyzed in axial compression, flexion, extension, left and right bending positions. Results: For nucleotomy group, the ROM and NZ were significantly increased and the disc heights were reduced. Once CoPP prothesis was implanted, the stability and height of the intervertebral disc restored to that of the intact disc group. Conclusions: The new CoPP prostheses can restore the stability and height of the intervertebral disc after nucleotomy, and this new kind of hydrogel prosthetic nucleus is hopeful in clinical application.