The memristive effect become a bio-electronics research focus with the development of sustainable systems and the application of multifunctional electronic devices. In this paper, the natural Lophatherum gracile Brongn (LGB) was employed as active layer to prepare Ag/LGB/fluorine-doped fin oxide (FTO) bio-memristor. Further, different doping ratios nano silver powders (Ag nanoparticle) were doped into LGB functional layers at 0 wt%, 0.2 wt%, 0.33 wt%, 1.0 wt%, 2.0 wt%, 10.0 wt% and 20.0 wt%. It is found that the capacitive-coupled memristive performance of the Ag/Ag-doped-LGB/FTO devices was markedly changed. Finally, it is confirmed that Ag ions transferring and Ag filament formation under the applied voltage are responsible for capacitive-coupled memristive behavior. This research has revealed the realization of capacitive-coupled memristive effect of bio-memristor, which opens a new way to achieve multifunctional performance for electronic device.