In order to ensure practice teaching to carry out smoothly in college and reduce accident, a safe and reliable, easy to use, portable security device was developed for offset machine. The device used a wireless transmitting/receiving technology, and closed contact of the relay on the wireless receiving output connects with manual brake button in the control system of the offset machine. When hidden danger occurs, it can stop the machine through the wireless transmitting end to realize fast remote shutdown operation, so as to protect personal and equipment safety.