The gold, hidden in a juicer and calender, is worth about Tk 70 million, according to Md Al Amin, the deputy commissioner of Sylhet Customs.
The detainees have been identified as Sheikh Md Jahid of Habiganj, Mokbul Ali, Mofiz Uddin and Sultan Mahmud, all from Sylhet.
Customs officials seized the shipments, acting on a tip-off that the passengers would arrive on a Bangladesh Biman flight from Dubai.
After the flight landed at 9 am, the customs officials interrogated and searched the luggage of four passengers and found the gold.
A gold smuggling case was filed against the detainees, Al Amin said.