Abstract: The subsea capping stacks is an emergency device used to temporarily contain subsea blowout well, reestablish 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.