A 16-year-old boy has been airlifted to hospital after he slipped and fell 20 metres from a cliff while bushwalking on a mountain in the Southern Downs.

Emergency services, including two helicopters, were called just after 8am on Friday to Mount Mitchell in Tregony, about 115 kilometres south-west of Brisbane.

Queensland Ambulance Service senior operations supervisor Stephen Johns said the boy fell down the cliff from the main entrance to Main Range National Park.

"He was 20 metres down the face of the mountain peak and two rescue helicopters were utilised in an attempt to winch the patient from the scene," he said.