To solve the problem that microstructure arrays is machined on the curved surface of parts, an electrochemical machining process with a linear cathode and a soft mask on a roller was proposed and used to machine micro-pit arrays on various surfaces of metal parts. An electrolytic system with a rolling printing mask was built and a rolling tool was designed. In this device, a copper linear (with diameter of 500 μm) was used as the cathode and a polyvinyl chloride (PVC) film with micro-hole arrays was used as the mask. The experiments were carried out on the surface of the 304 stainless steel workpiece under conditions of 10% NaNO3 electrolyte and 0.1 mm electrode gap. The effects of the voltage, the rotation speed of the cathode tool, and the cathode size on the morphology of micro-pit arrays were explored. The surface morphology of micro-pits on the workpiece was observed by ultra-depth field microscope, scanning electron microscope and Olympus microscope after the electrochemical machining process. The results showed that the micro-pit arrays on the surface of the workpiece could be machined and had high precision and high consistency under the electrolytic condition of 10.5 V processing voltage and 0.2 r/min rotation speed. The diameters of the micro-pits were in the range of 402.8-440.3 μm, the depth of them was between 66.2 μm and 74.2 μm, and the roughness range of the micro-pit was 0.42-0.83 μm. Compared with the electrolytic results using the traditional circular cathode, the diameter of the micro-pits produced by this electrochemical machining process with the linear cathode was reduced by about 100 μm, and the depth of the micro-pits was reduced by about 20 μm. The reason for this result was that the size of the linear cathode was so small and close to the size of the micro-hole on the mask, and the current density was concentrated mainly in the metal surface of the micro-holes on the mask during the electrolysis process, and there was no current distribution outside the processing area. However, because the size of the traditional circular cathode was much larger than that of the micro-hole on the mask and this circular cathode had a large range of the electric field distribution, the unprocessed area and the processed area of the workpiece surface were completely exposed to the electric field generated by the circular cathode in the electrochemical machining process. The redundant current distribution would cause micro corrosion or secondary corrosion on the unprocessed and the processed area, which lead to the deviation of the micro-pits diameter from the micro-hole on the mask and the poor localization of the micro-pit arrays. Furthermore, a large number of the micro-pit arrays were machined. The inner and the outer surfaces of the cylinder of 304 stainless steel workpiece were treated by the process and the device proposed in this paper. The experiment results shows that the electrochemical process with the linear cathode and the rolling printing mask has a significant and promising potential competitiveness in machining high-quality and high-precision microstructures on various surfaces of the metal parts.