Abstract:Based on an analyses to the characteristics of operation of synchronous motor being out of step,and its harmfulness with the help of computers. Some protection measures have been presented here. These protecting measures to be taken can make a motor contin ually running with load while the motor is out of step,at the same time the synchronization of the moter can be restored itself.This can not only avoid harms because of motor being out of step but also guarante the continuity production procedure.