Two Danish citizens, an American, a Briton and two Australians died following what media said was a night out in the town on November 12.
Police have detained the 34-year-old manager of the Nana Backpacker Hostel and seven other employees for interrogation, the Laos Post said on Tuesday.
Local media reported that all those detained were Vietnamese nationals.
Vang Vieng has been a fixture on the Southeast Asia backpacker trail since Laos' secretive communist rulers opened the country to tourism decades ago.
The town was once synonymous with alcohol and drug-fuelled jungle parties for backpackers but has since re-branded as an eco-tourism destination.
Alcohol tainted with methanol is suspected to be the cause of the deaths.
Methanol is a toxic alcohol that can be added to liquor to increase its potency but can cause blindness, liver damage and death.
On their travel advice websites, UK and Australian authorities have warned their citizens to beware of methanol poisoning while consuming alcohol in Laos.
On Saturday the Laos government expressed "sincere sympathy and deepest condolences to the families of the deceased", adding an investigation was underway to find the cause of the incident.
