Objective: To study the relationship between the ossification and degeneration of the ligamentum flavum, we compared the changes of Calcium (Ca), Phosphorus (P), Magnesium (Mg), Zinc (Zn), Cuprum (Cu), Manganese (Mn),Molybdenum (Mo) and Fluoride(F) in the ligamentum flavum and sera between patients with OLF and those with lumbar stenosis. Methods: The contents of Ca, P, Mg, Zn, Cu, Mn, Mo and fluoride in the ligamentum flavum and sera were detected by using atomic absorption, phosphomlybdic blue method and fluoride selected electrode. Results: There were similar changes of Ca, P, Mg, Zn, Cu, Mn and Mo in the ligaments and sera between ossification and degeneration of the ligamentum flavum, and fluoride was obviously higher in the ligamentum flavum of OLF. Conclusion: It is suggested that there is a tendency from degeneration to ossification of the ligamentum flavum, and fluoride plays an important role in the early stage of the process of the OLF.