  In the standard model QCD Lagrangian, a term of CP violating gluon density is
theoretically expected to have a physical coefficient $\bar{\theta}$ of the
order of unity. However, the upper bound on the electric dipole moment of
neutron enforces the value of $\bar{\theta}$ to be extremely small. Such a huge
gap between theoretical expectation and experimental result is commonly known
as the strong CP problem. To solve this puzzle in an appealing context of two
Higgs doublets, we propose an economical $\bar{\theta}$-characterized mirror
symmetry between two Higgs singlets with respective discrete symmetries. In our
scenario, the parameter $\bar{\theta}$ can completely disappear from the full
Lagrangian after the standard model fermions take a proper phase rotation as
well as the Higgs doublets and singlets. Moreover, all of new physics for
solving the strong CP problem can be allowed near the TeV scale.
