Film cooling holes are obtained by electrochemical machining using Inconel718 nickelbased superalloy which is commonly used for turbine blade of aeroengine.In the process of ECM, hydrogen is precipitated in the cathode reaction interface, which leads to the conductivity of the electrolyte no longer a constant. The influence of processing voltage, electrolyte inlet pressure and electrode feed rate on gas liquid two phase flow were studied based on COMSOL Multiphysics software and the relationship between hydrogen gas volume and electrical conductivity was analyzed qualitatively. The results show that the volume fraction of hydrogen increases with the processing voltage and the electrode feed rate, and decreases with the increase of the inlet pressure, and the greater the volume fraction of hydrogen, the smaller the conductivity of the electrolyte is.