Objective To study the changing of vertebral body marrow fat fraction(FF) in different age and sex and the relation-ship between FF and bone mineral densities (BMD). Methods Eighty-five healthy volunteers aged from 21 to 70 years old and twenty patients with osteoporosis based on T score after dual X-ray absorptionmetry examination underwent proton magnetic reso-nance spectroscopy (MRS) in L_3 vertebral bodies. The volunteers were divided into five groups according to the age(10 years and 16～18 cases in each group). Results The FF values in 21～30 years group,31～40 years group,41～50 years group,51～60 years group , >60 years group and the osteoporotic group were 30.7%±4.4%, 35.5%±6.8% , 41.9%±6.6%, 46.8%±5.5%, 51.7%±5.2% and 59.2%±7.4%, respectively. The FF values in L_3 vertebral bone marrow in men were high than that in women in the same age group (P<0.05) except >60 years group. There was negative correlation between marrow fat content and T score in osteoporotic group(γ=-0.6, P<0.01). Conclusion The vertebral marrow fat content in healthy adults was significantly in-creased with the aging. MRS may be used as a new way to evaluate the physiological and pathological process of bone marrow.