Bone metastasis of cancer is a common process that destroys the balance between osteoclast and osteoblast, causing skeletal-related events. Cancer bone metastasis is a complex and orderly process, including pre-metastasis niche, escape and home, colonization and dormancy, reactivation and growth. The extracellular matrix, blood vessels, various cells including immune cells and osteocytes, different factors like cytokines, growth factors, chemokines form the bone microenvironment, some of them make the tumor more prone to metastasis. In addition, primary tumors metastasize to bone through different signaling pathways. Understanding the mechanism of bone metastasis is very significant for exploring more effective treatment methods. This section introduces the mechanism of bone metastasis in different cancers.