Abstract: The disclosure relates to an electrolyte composite containing an oxide-based solid electrolyte, a method of preparing the same, and an all-solid-state battery containing the same, and more particularly to an electrolyte composite containing an oxide-based solid electrolyte that maintains high ionic conductivity to improve the performance of an all-solid-state battery, a method of continuously preparing the electrolyte composite in a mass production manner, and an all-solid-state battery containing the electrolyte composite.