Shubham, a class X student of a government school in Lahori Gate, tried to board an express train to Jalandhar from Shivaji Bridge railway station, a Railway Police official said.
The train does not stop at Shivaji Bridge but the boy, a resident of Ghaziabad, tried to board the train despite its high speed, he said.
He tried to put his foot on the footboard but was thrown off and sustained severe head injuries, he added.
The boy was taken to RML Hospital where he was declared brought dead by the doctors.