In [12,28], it was shown that the generalized Ricci flow is the gradient flow of a functional λ generalizing Perelman's λ functional for Ricci flow. In this work, we further computed the second variation formula and proved that a Bismut-flat, Einstein manifold is linearly stable under some curvature assumptions. In the last part of this paper, I proved that the dynamical stability and the linear stability are equivalent on a steady gradient generalized Ricci soliton (g, H, f ). This generalizes the results in [15,22,25,31,33].