Arsalan Motahhari gave Iran the lead in the 38th minute but two minutes later Chang Feiya levelled the match.
Ehsan Pahlavan restored Iran’s lead seconds later.
Mahdi Torabi made it 3-1 for Iran with a long-range free kick just three minutes after the break, although Liao Lisheng pulled a goal back from the penalty spot in the 70th minute.
Mohammad Khakpour’s men will meet Japan on Friday.
Elsewhere, Qatar defeated Syria 4-2 to secure first place in the group.