  The spontaneous CP-violation in three kinds of extension of the standard
model are investigated. We find that if no additional symmetry is introduced to
reduce the number of coefficients, then all three extended models possess the
spontaneous CP violation (SCPV) in the Higgs potential. When symmetry under
which the doublets transform as $\Phi_1 \to \Phi_1$ and $\Phi_2 \to
e^{i\gamma}\Phi_2$ is introduced, the two-Higgs doublet model will lose its
SCPV terms. In the other two extended models, the SCPV terms will be preserved
since both models contain at least one Higgs singlet which can appear in odd
powers. The extended model with two doublets and one singlet is reviewed and
the general conditions which make the CP-violating $V_{min}$ the true minimum
are given. The generally called natural flavour-conserving models are also
discussed briefly.
