Recently, rechargeable potassium-ion batteries (KIBs) have attracted a lot of attention due to the sufficient abundance and low redox potential of K. Anode, one of the important elements for batteries, directly determines their safety, cycle life, and energy density. Among various anodes, alloys can provide high theoretical specific capacity based on multi-electron reaction mechanism, which is promising to improve the energy density of full battery. Moreover, their K-storage voltages stay away from the deposition/stripping potentials of metallic K, thus enhancing the safety of batteries. However, the dramatic volume variation upon alloying and dealloying leads to electrode pulverization and capacity fading. What is an effective method to stabilize the structure of alloy-based anode is to construct the stable electrode-electrolyte interface by optimizing the electrolytes. It includes regulating the components of solid electrolyte interphase layers, adjusting the solvated structure of K+, and utilizing the chemisorption of solvent molecular on electrode. It takes the advantages of simple process and low cost. Here, this review covers the recent research progresses of the interfacial interaction between alloy anodes and electrolytes in KIBs, summarizes the optimization strategies of electrolyte, analyzes the potassium storage mechanisms and electrochemical performance of alloy anodes, and highlights the interfacial interaction mechanisms. Finally, this paper provides new insights for the future development of KIBs electrolyte.