The train stopped south of the town of Arras on Sunday evening "after an electrical incident on the engine car", Eurostar said in a statement.
Passengers were plunged into darkness and had to wait for the train to be pulled into Arras station, before catching another Eurostar.
Firefighters intervened to put out the blaze.
"There were no injuries," said an emergency services spokesman.
Passengers were supposed to arrive in Paris at 8:47 pm local time but only reached the French capital at 4:30 am.