Objective Based on the theory of "Brain as Marrow Sea", this paper analyzes the relationship between Alzheimer's disease (AD) and osteoporosis (OP), and explores the common pathogenesis of the two diseases, so as to spread the idea of prevention and treatment of OP. Methods The association between OP and AD was explored by searching CNKI, Wanfang, Pubmed and other databases on the theory of " Brain as Marrow Sea" and the ancient Chinese medical literature, clinical and experimental studies on OP and AD. Results The brain is the sea of marrow is from the Huangdi Neijing. The doctors' knowledge of the brain and the Sea of marrow is constantly deepening. They realize that the sea of marrow is full of nourishment for the bones, strong muscles and bones, intelligent and quick-witted, the bone and brain systems depend on each other physiologically through the marrow. OP and AD share the same physiological and pathological basis. Conclusion The theory of "Brain as Marrow Sea" is of great value in guiding the understanding of the common pathogenesis of AD and OP. Most doctors take the liver, kidney, spleen, muscle, bone and muscle as their guidance in the prevention and treatment of OP, we neglect the important role of brain-marrow, and expect to find out more ways to prevent and treat OP based on this theory. [ABSTRACT FROM AUTHOR]