A preliminary study of Numerical Controlled Electrochemical Turning (NC-ECT) technology was presented in this paper. NC-ECT is suitable for machining revolving workpieces which are made of difficult-to-cut materials or have low rigidity, and it is difficult or expensive for machining these workpieces by use of traditional turning or traditional Electrochemical Machining (ECM) method. To carry out the study, an experimental setup was developed on the basis of a common lathe, and a kind of inner-spraying cathode with rectangle section outlet was designed according to the process of machining cylindrical surface. First, the NC-ECT method was simply described. Then, considering the structure of the cathode and the process of machining, the method for calculating the inter-electrode gap in machining the cylindrical surface was given. Finally, the experiments of machining the cylindrical surface were carried out. Experiments showed that the calculated inter-electrode gaps are well consistent with the actual value of the machining process, which decreases with the increase of the rotational speed of workpiece and increases almost linearly with the increase of the working voltage. Experiments also showed that the inter-electrode gap keeps a certain relationship with the working current, the inter-electrode gap can be controlled according to working current in the machining process.