  In this paper we propose a possible explanation to the Fermion mass hierarchy
problem by fitting the type-II seesaw mechanism into the Higgs doublet sector,
such that their vacuum expectation values are hierarchal. We extend the
Standard Model with two extra Higgs doublets as well as a spontaneously broken
$U_X(1)$ gauge symmetry. All the fermion Yukawa couplings except that of top
quark are of order ${\cal O} (10^{-2})$ in our model. Constraints on the
parameter space from Electroweak precision measurements are studied. Besides,
the neutral component of the new fields, which are introduced to cancel the
anomalies of the $U(1)_X$ gauge symmetry can be dark matter candidate. We
investigate its signature in the dark matter direct detection.
