  Abstrct: We show that the action of self-dual supersymmetric Yang-Mills
theory in four-dimensions, which describes the consistent massless background
fields for $~N=2$~ superstring, generates the actions for $~N=1$~ and $~N=2$~
supersymmetric non-Abelian Chern-Simons theories in three-dimensions after
appropriate dimensional reductions. Since the latters play important roles for
supersymmetric integrable models, this result indicates the fundamental
significance of the $~N=2$~ superstring theory controlling (possibly all)
supersymmetric integrable models in lower-dimensions.
