Dorset Fire and Rescue were called at 20:20 BST to the site at Charles Trent Yard in Poole.
There are 11 fire engines, two water carriers, and as a command unit on site, with some roads around the area closed.
A spokesperson for Dorset Police said officers were assisting the fire service.
Firefighters are tacking a large fire that has broken out on a scrapyard in the Tower Park area of Dorset.