An innovative plastic deformation method is proposed to tune metal-based MEMS devices after fabrication. The plastic deformation is a well-known failure mechanism in MEMS devices, which includes a phenomenon that the devices do not return original position after repeated actuation. Here, in contrast to this common experience, we exploit the plastic deformation for the first time to tune the performance of MEMS devices, by producing deliberate, controlled plastic deformation with the help of Joule heating. The proposed plastic deformation method is precisely and predictably controlled by the model we developed here, and it was successfully demonstrated and evaluated using a fabricated MEMS device. Unlike conventional plastic deformation methods, the proposed method was accomplished solely by electrical control, which means that the method can be employed in integrated devices. Tuning resolution was demonstrated at a 10-nm level, which is remarkably smaller than that of conventional plastic deformation methods, where the tuning resolution is typically several micrometers. We confirmed that the proposed method does not deteriorate the basic performance of the fabricated MEMS devices. Finally, we proposed and demonstrated a method for calibrating MEMS devices after fabrication and suggested an interesting application, which is recovering the performance of aged MEMS devices.