All the victims were drivers and passengers on the bus, which was travelling from Kunming in China's Southwestern Yunnan province to Vientiane, Chinese embassy officials told Xinhua early Thursday.
The bus, which was carrying 25 passengers and three drivers, was shot by unidentified gunmen at around 9:00 pm local time (1400 GMT) on a road in Kasi, Vientiane province.
The driver was also wounded but he managed to drive the vehicle to safety. All the injured Chinese men were sent to a local hospital for treatment.
The shooting is the latest violence occurred in Laos this year. A Chinese national was killed and three others wounded on March 1 in an attack on a Chinese-invested company by unidentified gunmen in Luang Prabang province.