Electrochemical machining (ECM), an advanced manufacturing technology, is widely used in aero-engine blade machining. In blade ECM, the electrolyte flows through the inter-electrode gap, generating hydrogen bubbles and heat, which affect the conductance and thus influence the machining quality. This paper focused on the effect of bubble movement on the flow field and the machining quality of ECM. A novel vertical flow mode of electrolyte was proposed according to the bubbles dynamics analysis. Multi-physical field simulations of blade ECM using vertical and horizontal flows were carried out. With an initial gas void fraction and temperature at the inlet of 0 and 302.65 K, respectively, in both flow modes, the vertical flow reduced the gas void fraction and temperature at the outlet by 2.4% and 0.6 K, and increased the conductance by 0.47 S/m. Thus, the vertical flow of the electrolyte was beneficial in reducing the gas void fraction and controlling the temperature rise, while enhancing the conductance. Then, the corresponding experiments using a vertical flow were carried out. The machining deviation was found to range from 3.4 µm to 75.6 µm and surface roughness values of Ra < 0.35µm. The machining quality was high and the variation observed in the experiments was consistent with the simulation results, the validity and correctness of the simulations were verified. Thus, the vertical flow mode proposed in this paper was appropriate, can be used for other complex structures in ECM.