The subsea capping stacks is an emergency device used to temporarily contain subsea blowout well, reestablish blowout prevention system. This paper outlines subsea capping stacks' functional types of cap, cap and flow, and separated control method independent from the control of subsea bop stacks; introduces its deployment mode via drill pipe from a rig or wire from a vessel, three kinds subsea incident response toolkit and the order preference for attachment points; and summarizes the global resources and main technical parameters of subsea capping stacks.