Police and paramedics were called to the site next to the former Canal Works in the Manner Sutton Street area just before midday.
The Lancashire Telegraph reported that the victim had fallen from the roof of the building, which is currently being renovated and transformed into industrial units.
Paramedics made attempts to resuscitate the man, who has not yet been named, but he was pronounced dead at the scene.
Crime scene investigators moved in later and police also questioned a number of workers who were at the site before two men were driven away from the compound.