The 53-year-old from the Channel Island of Jersey was reportedly drunk when for some reason he decided to lie down on the track in the station in Rennes in Brittany, western France at around 3 am local time.
The driver of a freight train that was entering the station saw the man on the tracks and jammed on the brakes, but it was too late to stop the train in time, France Bleu radio reported.
The train ran over the victim, cutting off one of his feet and causing serious injuries to his head and abdomen. Ambulance workers arrived quickly and rushed him off for treatment at a nearby hospital.
The SNCF national rail company said it was not immediately clear how the man, who has not been publicly identified, managed to get into the station at that time of night, as it was closed to the public and security guards were on duty.
It is not clear whether the victim was a resident in the French city of Rennes or was visiting.