Objective Study the effect of load-dropping form on simulation result of osteoporosis based on the numerical model of postmenopausal osteoporosis. Methods Numerical model of postmenopausal osteoporosis was established based on the anisotropic bone remodelling model and mechanostat system combined wifh finite element method. Results Bone mass loses over 25% relative to premenopause when the load descends 20% due to fall of muscular strength and decrease of activities after menopause. Conclusion The result of research showed that both biomechanic factor and physiological factor can lead to osteoporosis,while the form of load descending had little influence upon result.