It is understood the man fell from a roof at a farm in the Craigavon area.
The emergency services rushed to the scene after the alarm was raised shortly before 1.30pm today at the Derrycarne Road.
Another man was seriously injured and is in Craigavon Area Hospital for treatment..
It is understood the men were constructing a barn when tragedy struck and they fell from the roof.
The Health and Safety Executive has now launched an investigation into the death.