It is necessary to develop a locking device for the magnetic suspended flywheel in a satellite launching. In this paper,a repeatable electromagnetic locking and unlocking device with a mass of 158 g and a dimension of 45 mm×49 mm×40 mm was designed for a magnetic suspended flywheel. The composition and working principles of the locking device were introduced and the mathematical models for locking and unlocking were established. Then,several kinds of tests,the sine vibration,random vibration and impact vibration were carried out to verify the locking device in ground and space environments,and the curves of the locking force versus displacement and the unlocking force versus displacement were given. Experimental results indicate that the max locking force is 650 N and the holding locking and unlocking forces are 133.8 N and -9.4 N,respectively,which shows the gravitation has a little effect on the locking device and it can realize locking and unlocking effectively.