It happened just before 4:30 p.m. Thursday on Limestone Road (Route 10) near Borough Line Road in Highland Township.
Officials say the driver lost control and struck a pole before the truck overturned.
Chopper 6 overhead after milk truck overturns in Chester County
Some of the milk spilled into a nearby creek.
Police say the unidentified driver was the only occupant of the truck.
The incident remains under investigation.