  Asteroseismology is a powerful tool for probing stellar interiors and
determining stellar fundamental parameters. In previous works,
$\chi^2$-minimization method is usually used to find the best matching model to
characterize observations. In this letter, we adopt the $\chi^2$-minimization
method but only using the observed high-precision oscillation to constrain
theoretical models for solar-like oscillating star KIC 6225718, which is
observed by \kepler\ satellite. We also take into account the influence of
model precision. Finally, we find that the time resolution of stellar evolution
can not be ignored in high-precision asteroseismic analysis. Based on this, we
find the acoustic radius $\tau_{0}$ is the only global parameter that can be
accurately measured by $\chi^2_{\nu}$ matching method between observed
frequencies and theoretical model calculations. We obtain
$\tau_{0}=4601.5^{+4.4}_{-8.3}$ seconds. In addition, we analyze the
distribution of $\chi^2_{\nu}$-minimization models (CMMs), and find that the
distribution range of CMMs is slightly enlarged by some extreme cases, which
possess both of larger mass and higher (or lower) heavy element abundance, at
lower acoustic radius end.
