The Middle East country has requested to purchase 44 THAAD launchers, 360 missiles, 16 fire control station and 7 radars, Xinhua quoted the said the statement as saying.
The sale was part of the $110 billion package of defence equipment and services initially announced during US President Donald Trump's May trip to Saudi Arabia, said an official from the US State Department on condition of anonymity.
"This potential sale will substantially increase Saudi Arabia's capability to defend itself against the growing ballistic missile threat in the region," said the statement from the Pentagon.
Congress has been notified about the possible sale and has 30 days to review the deal.
THAAD missile systems are deployed to defend against ballistic missile attacks.