  The absence of compelling theoretical model requires the parameterizing the
dark energy to probe its properties. The parametrization of the equation of
state of the dark energy is a common method. We explore the theoretical
optimization of the parametrization based on the Fisher information matrix. As
a suitable parametrization, it should be stable at high redshift and should
produce the determinant of the Fisher matrix as large as possible. For the
illustration, we propose one parametrization which can satisfy both criteria.
By using the proper parametrization, we can improve the constraints on the dark
energy even for the same data. We also show the weakness of the so-called
principal component analysis method.
