He is also due to meet President Fuad Masum, Foreign Minister Ibrahim al-Jaafari and parliament speaker Salim al-Juburi.
The UN mission in Iraq announced Ban's arrival on Twitter but provided no details of the agenda of the talks.
Iraqi forces are battling to retake the city of Tikrit, the government's largest military operation yet against the Islamic State jihadist group.
The fact that Baghdad is receiving military assistance from both the United States and Iran however has created tensions, internally and internationally.
He is expected to travel on to Kuwait for a meeting of international donors tomorrow called to address a massive funding gap in the response to the conflict in Syria.