Objective By biomechanical study about the stability of using 5 different types of pedicle screws (U1,U2,RF,SF1,SF2) on spinal specimen, to discuss the relationship between design parameter of screw,insertion torque,BMD and provide the theoretical foundation for clinical application of pedicle screw on osteoporotic patients; Method Six fixed lumbar cadaver specimens were used and divided into: normal group(ρ>1.00g/cm2, low BMD group (0.90g/cm2<ρ<1.00g/cm2)and osteoporosis group(ρ<0.90g/cm2). To determine the effects of the design parameter and the insertion torque of different screws on their fixation stability under various BMD by using WD-10A testing machine; Result There is a significant difference on the pullout strength of 5 different screws (U1,U2,RF,SF1,SF2) (P<0.05) . BMD of bone directly affect the intensity of fixation(according to the measured pullout strength). There is a significant difference among group of normal, low BMD and osteoporosis (P<0.05); The fixation intensity is in positive relation with insertion torque, the bigger the torque, the greater the fastness. And it is also in positive relation with BMD(r=0.936); Among specimens of low BMD, U2 has the greatest pullout strength among the 5 screws. Conclusion There is a close relationship between the type of screw, BMD and stability. BMD is in the positive relationship with pullout strength and insertion torque. In this study, the "U"-type screw displays the best fixation effect on specimen of low BMD