Terminal J was evacuated and shut down about 7 a.m. after a suspicious item was found at a security checkpoint, WFOR-TV, Miami, reported.
The closure occurred when a bomb-sniffing police dog alerted its handler to an item on a pallet.
Airport security evacuated the terminal and moved planes away from it.
A bomb squad from Miami-Dade police was called investigate the item.
The terminal reopened just before 9 a.m. Airport officials said no flights were delayed.