It is very difficult to execute the finishing process of the concavo-convex surface of female-screws. The current study offers a screw-form design electrode and a new area-finishing process using an ultrasonic generator. The ultrasonic energy generated is transmitted into the electrolyte to assist the process of electrochemical finishing. The surface of female-screws is electrochemically finished by different types of completely inserted electrodes and put through both continuous and pulsed direct current as a finishing operation. For inserted screw-form electrodes, a smaller circumference electrode on the cylinder provides more sufficient discharge space, which is advantageous for finishing. Pulsed direct current can promote the effect of electrochemical finishing, but the machining time is longer and the cost is raised. The average ultrasonic effect is much better than the pulsed current while the machining time needs not be prolonged by the off-time. The higher current density and higher current rating with ultrasonic assistance can avoid the difficulty of dreg discharge, thus reducing the finishing time. It is a great contribution that the ultrasonic-assistance electrochemical finishing after screw machining requires a shorter time than manual or machine polishing to make the surface of female screws smooth and bright.