Just seen a C17 Globemaster painted in civilian Qatar Airlines livery.
Any idea for the reason? Is this aircraft for civilian or a military use?
It is a military C-17 of the Qatar Air Force, one of the four in operation.
It is in this livery as it is being operated by the Qatar Amiri Flight, a VIP airline owned and operated by the government of Qatar. The vast majority of the Qatar Amiri Flight fleet is painted in the standard livery of Qatar Airways, like this A340 below.
The aircraft is only operated by the Qatar Amiri Flight, not owned by it. The picture below shows the Qatar Air Force roundel on the underside of the wing.
It is for military use. As you can see from your photo, the registration code is "MAB" and this site links that aircraft to the Qatar Emiri Air Force: