Object: To study the effect of Resection of the facets and discs on the lumbar Stability in lumbar disc protrusion. Method: Lumbar specimens from eight fresh cadavers were biomechaniclly analysed and compared in flexion, extension and left and right lateral bendings. There was a variety of stability after L4-5 bilateral graded facetectomy. Result: The decompressed recess with resection of a half of the processes in lumbar disc protrusion was significantly different from the normal subjects in the stress, the displacement and ROM(P<0.05). Conclusion: (1)The ertent of resection to the decompression of the recess is completely enough in the treatment of lumbar disc protrusion. (2)If facetectomy of a half of the processes is needed, there an internal fixation should be added.