The man was boarding a Perth-bound train about 8:50am when he slipped and became stuck.
Transperth spokesman David Hynes said the man was boarding at the tail end of peak hour, but the train was still fairly busy.
"He stood in the doorway and as he was sort of taking up his position there, one leg slipped outside the door, slipped outside the gap, and he was stuck," he said.
"We alerted the driver, made sure the train didn't move.
"Then our staff who were there at the time got the passengers, and there were lots of them, off the train, and organised them to sort of rock, tilt the train backwards away from the platform so they were able to get him out and rescue him."