State news agency IRNA said Xi, accompanied by three deputy premiers and six ministers as well as a high-ranking business delegation, was greeted at Tehran airport by Iranian Foreign Minister Mohammad Javad Zarif.
The president, who has already visited Egypt and Saudi Arabia, was to meet Saturday with his Iranian counterpart Hassan Rouhani and the Islamic republic's supreme leader, Ayatollah Ruhollah Khamenei, according to local media.
Beijing is Tehran's top customer for oil exports and trade between the two countries was worth $52 billion in 2014.
Iranian Deputy Foreign Minister Ebrahim Rahimpour has told state television that 16 accords including a strategic cooperation agreement are to be signed during Xi's visit.