The accident happened at 4.20pm on the Mitchell Line of Road near the Golden Highway, approximately 2km west of the New England Highway.

Police said the driver, a man who is yet to be identified, died at the scene.

The NSW Police Force Crash Investigation Unit (CIU) despatched officers from its Newcastle unit and from its Metropolitan unit, based at Huntingwood in western Sydney.

A crime scene was established.

Police said investigations into the cause of the crash are continuing and a report will be prepared for the Coroner.

The Golden Highway was closed following the truck crash, with westbound motorists diverted along the New England Highway and eastbound motorists diverted on to Range Road.

The region's rescue helicopter was tasked to the accident scene, but was later stood down when emergency services personnel established the trapped driver had passed away.

Earlier, Hunter Valley Local Area Command duty supervisor, Sergeant Jason Freney, told Fairfax Media the accident was a serious one.

"We have officers at the scene and are calling in crash investigators," he said.

Sergeant Freney said it was likely the Golden Highway would be closed for some time.

"We urge motorists to consider altering, or delaying, their travel plans while police carry out their investigations," he said.