Owing to the expanding function of Li-ion transmission channels, it is important to explore the doping effects of different compounds into sulfide solid electrolytes to improve their electrochemical performances. However, it is hard to characterize the doping behaviors within sulfide solid electrolytes with low crystallinity and poor stability just by conventional crystallography analytical methods. In this work, the dielectric spectrum testing combined with other analytical methods, such as 7Li solid-state nuclear magnetic resonance, X-ray photoelectron spectroscopy, and the electrochemical method, have been applied to investigate the dual-doping behaviors of WS2 and LiBr within Li7P3S11 glass-ceramic electrolytes. This research method can not only evaluate the internal acting effect between the skeleton of sulfide solid electrolytes and the migrating kinetics of Li ions but also explore the capacitance at the interfaces of LiCoO2/sulfide solid electrolytes. The experimental results show that the number of Li ions with fast transport velocity within Li2S-P2S5-based solid electrolytes has been increased. Meanwhile, the interfacial capacitances between Li2S-P2S5-based solid electrolytes and the LiCoO2 cathode have decreased after dual-doping of WS2 and LiBr, indicating a synergetic effect for the doped Li7P3S11 glass-ceramic electrolytes in terms of the ionic conductivities and interfacial compatibilities. This work may provide a novel analytical approach to explore both the diffusion kinetics and interfacial behaviors for the solid electrolytes of lithium batteries.