  The detached eclipsing binary stars with convective cores provide a good tool
to investigate the convective core overshoot. It has been performed on some
binary stars to restrict the classical overshoot model which simply extends the
boundary of fully mixed region. However, the classical overshoot model is
physically unreasonable and inconsistent with the helioseismic investigation.
An updated model of the overshoot mixing was established recently. There is a
key parameter in the model. In this paper, we use the observations of four
eclipsing binary stars, i.e., HY Vir, YZ Cas, $\rm{\chi^2}$ Hya and VV Crv, to
investigate the suitable value for the parameter. It is found that the
suggested value by the calibrations on eclipsing binary stars is same as the
recommended value by other ways. And we have studied the effects of the updated
overshoot model on the stellar structure. The diffusion coefficient of the
convective/overshoot mixing is very high in the convection zone, then quickly
decreases near the convective boundary, and exponentially decreases in the
overshoot region. The low value of the diffusion coefficient in the overshoot
region leads to weak mixing and the partially mixed overshoot region. The
semi-convection, which appears in the standard stellar models of low-mass stars
with convective core, is removed by the partial overshoot mixing.
