  Based on the Z_{12-I} orbifold compactification of the heterotic string
theory, we construct a flipped-SU(5) model with three families of the standard
model matter and ingredients for dynamical supersymmetry breaking. The
doublet-triplet splittings in the Higgs representations 5_{-2} and \bar{5}_{2}
are achieved by the couplings 10_{1}10_{1}5_{-2} and
\bar{10}_{-1}\bar{10}_{-1}\bar{5}_{2}, where 10_{1} and \bar{10}_{-1} develop
GUT scale vacuum expectation values, breaking the flipped-SU(5) down to the
standard model gauge group. In this model, all the exotic states are decoupled
from the low energy physics, and sin^2\theta_W^0=3/8. Above the
compactification scale, the flipped-SU(5) gauge symmetry is enhanced to the
SO(10) gauge symmetry by including the Kaluza-Klein (KK) modes. The hidden
sector gauge group is SU(5)'. The threshold correction by the KK modes allow a
very wide range for the hidden sector confining scale (10^{11} GeV -- 10^{16}
GeV). One family of hidden matter (\bar{10}' and 5') gives rise to dynamical
supersymmetry breaking.
