The CAT 775D service truck was descending a ramp at the coal mine that had recently been watered.
The truck began to slide for about 50m, before gripping on the dry line of the ramp, resulting in the truck overturning on to the driver's side.
The operator was not injured, the New South Wales Resources Regulator said in an alert.
"All personnel who operate rubber-tyred, heavy mining equipment should be trained on driving techniques in wet conditions," it said.
"Management plans and procedures should identify ramp and cresting speed limits."