This adapter is a kind of firefighting equipment provided for high buildings subject to the “Firefighting Standard For High Building”. It is usually connected to the auto sprinkler system or hydrant or other water supply system for firefighting equipment inside the building. In case of fire, the water pump of fire engine can be easily connected to the firefighting equipment inside the building via the adapter and supply and pressurize water to indoor firefighting equipment, providing sufficient pressure and water for the extinguishments of fire in different floors. It has effectively solved the difficulties of extinguishments due to the problem of fire engine of insufficient water pressure or water source for indoor firefighting equipment.