The two sides have already agreed a fee for the Cardiff captain and the deal has now moved a step closer.
The central defender is expected to sign for QPR before flying out to Germany and joining up with the squad for the club's pre-season tour.
Caulker would join Rio Ferdinand at Loftus Road, after he completed a move from Manchester United last week.
The two clubs are understood to have agreed a fee in the region of £8million for the 22-year-old centre-back.
The R’s are facing their first season back in the Premier League following one season in the Championship which culminated with a dramatic play-off final win over Derby County.
QPR manager Harry Redknapp has admitted he is looking to add players who are already proven in England so they are ready to make an immediate impact.
"I want lads that want to have a go - you just have to hope you can get them," he said. "You can take chances with too many foreign players.
“In the main I like players that have played in England and proved they can do it here rather than wait six months to see if they settle in - we haven't got six months.
"We need to stay in the league this year so we know what we are getting with the Caulkers and the Rios. We are looking at another English striker so if I can get British players in the main then I will."