A Chinese businessman has pleaded guilty to helping Chinese military hackers in stealing sensitive US military secrets.

A US Justice Department statement said businessman Su Bin was part of a group that carried out a years-long conspiracy to hack into the computer networks of major US defense contractors.

They plotted the theft of sensitive military secrets and export-controlled data and send the stolen data to China.

Su Bin, also known as Stephen Su and Stephen Subin, pleaded guilty before US District Judge of the Central District of California.

The 50-year-old businessman is involved the aviation and aerospace fields. He was initially arrested in 2014 after a criminal complaint was filed for his role in the conspiracy to steal military technical data, including data relating to the C-17 strategic transport aircraft and certain fighter jets produced for the US military.

"Su Bin admitted to playing an important role in a conspiracy, originating in China, to illegally access sensitive military data, including data relating to military aircraft that are indispensable in keeping our military personnel safe," a senior Justice Department official said.

But the DOJ did not specifically say the Chinese government had a role in the cyber attacks on US.

Su faces five years in prison and a $250,000 fine.