At 1am, soldiers and immigration police stopped a van with the Chinese passengers at a checkpoint in Mae Sot district.
The Chinese, who worked in Myanmar and crossed the border into Thailand via the Moei River, had expired visas.
All of them were promptly arrested, together with the van driver and another Thai passenger.
The six Chinese were charged with illegal entry, while the two Thais were arrested for helping foreigners illegally enter the country.