  The dynamics of the charge equilibration (CE) and the effects on the
production of the neutron-rich isotopes around $N = 126$ in multinucleon
transfer reactions are still not well understood. In this Letter, we
investigate the mechanism of the CE from different viewpoints by using the
extended version of the dinuclear system model (DNS-sysu) and the improved
quantum molecular dynamics (ImQMD) model. From the macroscopic and microscopic
dynamical viewpoints, we find incomplete CE for the mass asymmetry reaction
systems even in the very deep collisions, and the behavior of "inverse CE" that
the tendency of the fragments is away from the $N/Z$ value of the compound
system in the reaction $^{140}$Xe + $^{198}$Pt. Unlike the slow process
presented in the ImQMD model, the behavior of fast equilibration with the
characteristic time $\sim$ 0.52 zs is obtained based on the DNS-sysu model,
which is consistent with the experimental data. By performing the systematic
calculation, the correlation between the CE and the mass asymmetry of the
reaction systems is clarified, which not only accounts for the observed
intriguing phenomena of the CE but also provides essential information for
producing the neutron-rich isotopes around $N = 126$.
