The 15 consultation fees came to $1800.
Mr Ouyang said he understood that the DHB had to charge, but he hoped the victims' travel company would reimburse him.
He had also opened his restaurant and provided free food for 18 crash victims.
"They hadn't eaten all the day, they only had the breakfast in Christchurch."
He spent about eight hours with the victims last Thursday, trying to reassure and cheer them up.
The DHB's director of nursing and midwifery, Karyn Bousfield, said Grey Hospital treated eight patients with moderate injuries.
The other passengers were treated at the crash scene then taken to Greymouth's Holy Trinity Church while their tour company organised overnight accommodation, Ms Bousfield said.
Passengers who wanted further medical assessments were sent to the clinic.
Ms Bousfield said they were charged at the standard rate for foreign nationals of $120 per procedure. They were not charged for dressings, which would normally incur an extra fee, Ms Bousfield said.
A Victim Support worker had also bought clothing for a patient whose clothes had to be cut off for medical assessment. But Ms Bousfield denied that the hospital had refused to provide painkillers, resulting in a Victim Support worker buying them from a supermarket.
"Staff suggested the purchase of Paracetamol/ Ibuprofen at the supermarket, in case any of the passengers felt a bit sore. It was not prescribed and it was not a directive," she said.
Thirty-six tourists were involved in the late-morning crash on New Year's Eve.
The bus rolled on to its side after colliding with a car at Windy Point between the Otira Viaduct and Otira Village on State Highway 73, near Arthurs Pass.
Three Swiss nationals were travelling in the car towards Christchurch and the remainder were Chinese on the tour bus, which was heading to the West Coast.
Eight passengers were transferred by road to Christchurch Hospital. Another eight went to Christchurch Hospital, seven by air and one by road.
Police took 15 uninjured passengers to Greymouth.
Nine victims still in hospital are improving. Eight are in a stable condition and one has improved from critical to serious.
A police investigation continues into the cause of the crash, including possible brake failure on the bus.