Leading a high ranking delegation, Halaqi was welcomed by his counterpart Mohammad Reza Rahimi.
According to the Fars news agency, he is expected to meet Iran's supreme leader Ayatollah Ali Khamenei and President Mahmoud Ahmadinejad, as well as parliament speaker Ali Larijani.
Fars said the two sides will discuss "expansion of bilateral relations and Syrian President Bashar al-Assad's three-step plan" for the political future, presented on January 6.
Assad's plan was rejected by the opposition and Western governments as being detached from reality. The plan offered dialogue but only with opposition groups he deemed acceptable, not "terrorists" led by foreigners.
Iran has supplied financial aid to Syria and has admitted to sending military advisers to assist in the regime's nearly 22-month crackdown.
According to UN figures, more than 60,000 people have been killed in the violence in Syria since March 2011.
Halaqi's visit to Iran comes a week after Syrian rebels freed 48 Iranians held hostage for more than five months in exchange for more than 2,000 regime detainees.