Abstract: The guide pendulum of one machine in a factory decreased sharply after the shear pin was cut, because the guide pendulum of the machine was seriously over the standard before the shear pin was cut, but the guide pendulum data became qualified after the shear pin was cut, and the other data did not exceed the standard. Therefore, it is necessary to analyze the phenomenon from the angle of force, the change of stability and the change of the temperature of the water guide bush. On this basis, some reasonable suggestions are put forward for the operation and maintenance of the unit.