"Our boss deducts money for staying at his property and meals at the restaurant, so effectively, they will just be getting about $8 an hour," he said.
"I have been told to either match this, or face having to go back to China when my working visa expires in March."
The union said it was seeing about three cases of migrant workers complaining of being paid below the minimum wage each month, but could not say if any were linked to Immigration's China special work category.
"We are hearing that Chinese and migrant workers are getting $10 an hour," said the union's migrant support co-ordinator, Dennis Maga.
People who complained to the union did not lodge official complaints for fear of losing their visas and right to remain in the country.
John Howard, Department of Labour general manager, said the department has not received complaints specifically linked to the China special work visas.