China's government asked the National Audit Office (NAO) in July to do a round-up of the debts outstanding at a local level.
The report showed some local governments were using new loans to repay more than a fifth of their debt.
China has a total government debt of about 58% of its economic output.
Persistent fears over the level of non-performing bad debt have affected perceptions of the world's second-largest economy, as some worry whether the loans can be paid back.
The figure is still less than half the debt burdens in Japan - the world's third-largest economy -  and Greece, but some analysts warn that China's debt cannot continue to grow at this pace forever.
"While China's total government debt remains low by the OECD standards, the pace of the rise is still alarming," said ANZ Bank economists Liu Li-Gang and Zhou Hao.
"This national debt audit result could indicate that China's local government debt almost doubled in about two-and-a-half years."
According to the China Banking Regulatory Commission, local governments took up 80% of total bank lending in China at the end of 2010. Local governments in China borrowed heavily after the global financial crisis, to try to sustain growth rates.
The Chinese central government has repeatedly stressed the urgent need to guard against financial risks, including the local government debt problem.

The 46-year-old, who met the Scottish Championship club's board on Friday morning, succeeds Ian Murray, who resigned on Saturday.
Rae left Genk in the summer, having been assistant manager to Alex McLeish at the Belgian top-flight club.
It will be his second stint as a manager in his own right, having had a two-year spell at Dundee from 2006.
The Press Association has reported that Buddies chairman Stewart Gilmour originally wanted to hand Rae a short-term contract until the end of the season.
But a statement on the club's official website said: "The new manager has signed a deal that will see him take charge until at least the summer of 2017."
Rae's spell at Dundee was also in Scotland's second tier and he takes over in Paisley with the Buddies sitting third bottom ahead of Saturday's visit to bottom side Alloa Athletic.
Murray's six-month reign ended after a defeat by Dumbarton, the club he left in the summer to replace Gary Teale, who was sacked following St Mirren's relegation from the top flight.
Rae was appointed player-manager at Dens Park in May 2006 and they finished third then second in the old First Division in his first two seasons in charge.
However, having already retired from playing, he was sacked as manager in October 2008 with his side sitting eighth in the table.
He joined Milton Keynes Dons as first-team coach under Paul Ince and then moved to Notts County and Blackpool as assistant manager to the former England midfielder.
After Ince was sacked in January 2014, Rae teamed up with McLeish at Genk until the former Scotland manager left the Belgian club in the summer.
Rae's playing career began with Falkirk and he subsequently was on the books of Millwall, Sunderland, Wolverhampton Wanderers and Rangers before he joined Dundee.
He briefly revived his playing career as cover for injuries while with MK Dons.

The 23-year-old, who joins from Weston-Super-Mare, turned down interest from Swedish top-flight side Ostersunds to join the Spitfires.
Eastleigh boss Chris Todd said: "I am excited to have Scott join the squad.
"He is an incredibly hungry individual who is looking to succeed in the game and has a huge desire to progress with Eastleigh."
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China has local government debts of 17.7 trillion yuan ($2.9tn), up 70% from three years ago, according to an official report.
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Former Rangers and Wolves midfielder Alex Rae has become St Mirren manager after signing an 18-month contract.
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National League side Eastleigh have signed striker Scott Wilson on a one-year contract.