Micro-dimples are the basic surface textures that have played an important role in reducing or increasing friction, anti-wear, decreasing vibration, anti-adhesion, and creeping. Electrochemical micromachining (EMM) is a popular method for preparing micro-dimples. The method of sandwich-like electrochemical micromachining (SLEMM) can be used to enhance machining accuracy of micro-dimples, due to the electrolytic products accumulated on the workpiece surface in the enclosed unit of SLEMM. Therefore, this paper focuses on exploring the influence of bubbles accumulated on the workpiece theoretically and experimentally. The theoretical analysis indicated that 0.2 s machining time is required, and the theoretical maximum depth of micro-dimple is 7.3 mu m when the electrochemical dissolution reaction is terminated. The CCD camera was employed to observe the process of SLEMM, and the observations indicated that the changes of gas bubbles are very complex and the electrolytic products accumulated on the workpiece surface have a significant influence on the preparing of micro-dimples. In addition, the experimental results indicate that the dimensions of micro-dimple vary little and the maximum depth of 4 mu m for micro-dimples could be prepared with the increase of applied voltage, machining time, and thickness of mask, because of the electrolytic products accumulated on the workpiece during SLEMM. [GRAPHICS] .