  We study the stabilities of (A)dS charged Gauss-Bonnet(GB) black holes in the
large $D$ dimensions. After integrating the equation of motion with respect to
the radial direction, we obtain the effective equations at large $D$ to
describe the nonlinear dynamical deformations of the black hole. From the
perturbation analysis of the effective equations, we get the analytic
expressions of the frequencies for the quasinormal modes of scalar type.
Furthermore we show that the charged GB black hole becomes unstable only if the
cosmological constant is positive, otherwise the black hole is always stable.
At the onset of instabilities there is a non-trivial static zero-mode
perturbation, which suggests the existence of a new non-spherical symmetric
solution branch of static dS charged GB black holes. We construct the
non-spherical symmetric static solution of the large $D$ effective equations
explicitly.
