The MPs are alleged to have received bribes a year ago from the then opposition leader, Moana Carcasses, who is now deputy prime minister.
It is alleged that $US319,000 were involved.
Mr Carcasses was allegedly trying to procure the MPs support before a planned vote of no confidence to remove the then prime minister Jo Natuman.
Our correspondent in Vanuatu says sources say the money involved may have come from a businessman in Hong Kong.
Another three MPs, who had been facing charges, are now prosecution witnesses.