Two fire engines from Thorne and Doncaster stations were called to the site of the fire in Stainforth at 12.15pm.
The blaze is visible to motorists on the nearby M18 motorway between Thorne and Doncaster with clouds of grey smoke rising into the sky.
The fire is near to the former Hatfield Colliery pit head site.
People living in nearby Mayfield Avenue have been keeping a close eye on the flames.
Resident Alex Fodor said: "I think people will be concerned about this. It could be spreading. I think its dangerous."
Sarah Stephens added: "It's quite alarming. I took the dog for a walk earlier but that was towards the canal. It wasn't that bad at the time. That looks like it could be dangerous."
Another resident who did not want to named said : It looks like its spreading. They don't seem to be putting any water on it. It scares me in can an ember comes this way. I'd worry about the wind changing. It's a really big site there. We saw a train passing through the smoke earlier."
David Beddoes said: I knew there was a fire up there. There were two fire engines last night. I assumed they'd put it out. The grass is really dry but I don't think it will get as far as here. There's no road up there so they'll have walk up to fight it."
It is not known how the fire started and no-one is understood to have been hurt.
(Photos: Tony Thresh)