Electrochemical metallization theory is widely adopted to interpret the process of conductive filaments (CF) formation and rupture in electrolyte based resistive switching memory. However, this theory generally suit the situation of fast ionic mobility. For material system with low ionic mobility, there exist some controversies with the conventional electrochemical metallization theory. In this work, we performed real-time characterization of resistive switching in binary oxide electrolyte based RRAM. We found the CF was grown from the anode instead of the cathode. Thus, modified microscopic mechanism based on the local redox reaction inside the ZrO 2 -electrolyte system was suggested to account for observed RS effect.