Considering the influence of hydrogen gas generated during electrochemical machining on the conductivity of electrolyte, a two-phase turbulent flow model is presented to describe the gas bubbles distribution. The k-ε turbulent model is used to describe the electrolyte flow field. The Euler-Euler model based on viscous drag and pressure force is used to calculate the two-dimensional distribution of gas volume fraction. A multi-physics coupling model of electric field, two-phase flow field and temperature field is established and solved by weak coupling iteration method. The numerical simulation results of gas volume fraction, temperature and conductivity in equilibrium state are discussed. The distributions of machining gap at different time are analyzed. The predicted results of the machining gap are consistent with the experimental results, and the maximum deviation between them is less than 50 μm.