In order to solve the problem of poor processing quality caused by uneven distribution of flow field during the process of square holes by electrochemical machining (ECM) with tube electrode, a method of workpiece vibration-assisted ECM of square holes with tube electrode is proposed. The results of flow field simulation indicate that workpiece vibration-assisted ECM can generate obvious pulsating flow fields at different positions within the machining gap, improve the electrolyte flow state within the machining gap and effectively eliminate the stagnant water area within the machining gap in the traditional ECM of square holes, thus facilitating the discharge of electrolytic products and improving the stability of ECM. The experimental researches were also conducted at the same time, and the results show that the use of workpiece vibration-assisted ECM with tube electrode can improve the contour accuracy and surface quality of square holes machining, and the use of pulse current can further improve the quality of square holes machining. Finally, a square hole with an average width of 1.218 mm, width standard deviation of 0.026 mm, side-wall surface roughness of 0.703 μm was electrochemically machined by using the amplitude of 0.04 mm, the vibration frequency of 20 Hz, the pulse duty cycle of 80%, the pulse frequency of 5000 Hz and the feed speed of 1.5 mm/min.