Raj Kumar, 45, suffered critical injuries and died when the train hit him after he leaped onto the track from platform number 1 at the Jahangirpuri metro station in north Delhi around 2.20 p.m.
The Yellow Line train was on its way to Huda City Centre in adjoining Gurgaon in Haryana, its destination.
"Raj Kumar was rushed to Babu Jagjivan Ram hospital where he succumbed to his injuries," a police officer said.
He was identified as a resident of Jahangirpuri from an identity card recovered from his possession.
"The reason behind the suicide is yet to be known," the official said.