Brenden Jacob Bennetts has admitted killing Gatton schoolgirl Jayde Kendall but denies murdering the 16-year-old.
Bennetts pleaded not guilty to murder in the Brisbane Supreme Court on Monday but guilty to the lesser charge of manslaughter.
He also pleaded guilty to interfering with a corpse.
Bennetts, 21, was charged with killing Jayde after her body was found in a paddock, two weeks after she disappeared in August 2015.
Prosecutors rejected Bennetts' guilty plea to manslaughter, meaning he will still face a two-week trial for murder.
A jury is due to be empanelled on Monday morning.