The incident happened yesterday when the 15-month-old baby's
grandmother looked away for a moment.
Security camera footage shows the pushchair rolling towards the edge and then tipping off the platform just as the train pulls into the station.
It was pushed a short distance down the tracks before the train came to a halt.
The dramatic escape came just seven months after another baby in the southern city of Melbourne survived a train striking his buggy, which had also rolled on to the tracks.
Paramedic Kate Jessop said officials were amazed the child survived.
"It's absolutely amazing that this child isn't more injured than what he is, given the circumstances of the accident," Ms Jessop told reporters. "It would appear, amazingly, that it's nothing more than a couple of grazes and a big fright.
"I was assuming the worst as well and had those awful pictures in my head of a child underneath the train."
The baby and his three-year-old brother were being cared for by their grandmother. She told officials she looked away for a moment, and turned back to see the pushchair on the track, Ms Jessop said.
Officials have not released the name of the grandmother, and paramedics said she was too distraught to talk.
The boy was in stable condition in hospital with minor facial bruising and grazes to his head.