Mr. Sarkozy faces accusations that his party falsified accounts in order to hide 18m euros (£15m; $20m) of campaign spending in 2012, the BBC reported.
Mr. Sarkozy denies he was aware of the overspending, and will appeal against the order to stand trial.
He lost the 2012 race, and failed in his bid to run again in this year's upcoming presidential election.
The case is known as the Bygmalion scandal.
It centers on claims that Mr. Sarkozy's party, then known as the UMP, connived with a friendly PR company to hide the true cost of his 2012 presidential election campaign.
Read alsoFillon wins France presidential primaryFrance sets limits on campaign spending, and it is alleged the firm Bygmalion invoiced Mr. Sarkozy's party rather than the campaign, allowing the UMP to exceed the limit.
Employees at Bygmalion have admitted knowledge of the ruse and several UMP members already face charges.
The investigation into Mr. Sarkozy centers on whether the ex-leader was aware of the alleged fraud.
Thirteen other people are also expected to be tried.
However, Mr. Sarkozy's lawyer, Thierry Herzog, has said he will launch an appeal against the trial order, because only one of the two judges handling the case signed the order.
"The clear disagreement between the two magistrates in charge of the matter is such a rare event that it is worth underlining, as it illustrates the inanity of the decision," Mr. Herzog said in a statement.