Da Nang authorities on Monday checked a local tourism company and found five Chinese men working there illegally for months.
The Chinese nationals entered Vietnam on tourist visas and had been working for the company Nature Love as accountants and tour guides, Tran Chi Cuong, deputy head of the Tourism Department, told local media.
Each of them was fined VND20 million, or around US$900.
The department also imposed a VND12.5 million fine on Nature Love and banned the company from offering international tour services for two years.
Earlier this month the city had fined six other Chinese nationals for similar violations.
Last week the Vietnam National Administration of Tourism called on Da Nang authorities to check the operations of all travel agents and expel illegal Chinese tour guides following accusations that they distorted Vietnamese history while showing tourists around.
The violators could also face a ban on entering Vietnam ever again.