  The black hole superradiance phenomena state that when a scalar wave
perturbation is properly scattering off a charged or rotating black hole, the
energy of the reflected scalar wave may be amplified. If this amplification
process can occur back and forth through certain confining mechanisms, it will
lead to strong instability of the black hole, which is so-called "black hole
bomb". In this paper, the superradiant stability is investigated for dyonic
black holes in string theory. Although the electric charged black hole in
string theory has been proved superrdiantly stable, it is found that the dyonic
black hole is more unstable than an RN black hole due to the magnetic charge.
Furthermore, by our analysis of the effective potential outside the event
horizon, we give the region of the parameter associated with the superradiance
stability on dyonic stringly black hole.
