  We present a preliminary result of Nf=2+1 QCD running coupling in
Schroedinger functional scheme. We adopted Iwasaki gauge action and
non-perturbatively improved Wilson fermion action with clover term. We use
seven renormalization scales to cover from low energy to high energy
perturbative region and three lattice spacings to take the continuum limit at
each scale.
  A scaling behabior of the step scaling function is discussed together with
its renoralization group flow in the continuum. We argue on introduction of the
physical scale through the Sommer scale r0.
