  In this paper, in a class of warped compactifications with the brane/flux
annihilation, we find that the inflation may be driven by a flat direction
identified as that along the number p of anti D3-branes located at the tip of
the Klebanov-Strassler throat. The spectrum of adiabatic perturbation generated
during inflation is nearly scale invariant, which may be obtained by using the
results shown in the phantom inflation, since in a four-dimension effective
description the evolution of energy density along the $p$ direction is slowly
increasing.
