The utility model discloses an external shield constructs stone crusher agitating unit, the stone crusher include swing joint's jaw no. 1 and jaw no. 2, one side the fixedly connected with extension bar no. 1 and extension bar no. 2 respectively of jaw no. 1 and jaw no. 2, extension bar no. 1 and extension bar no. 2 respectively with hydraulic cylinder no. 1 and two swing joint of hydraulic cylinder, opposite side the fixedly connected with stirring rod no. 1 and stirring rod no. 2 respectively of jaw no. 1 and jaw no. 2. The utility model discloses respectively weld the stirring rod on two jaws of stone crusher, at the swing in -process that the stone crusher moved in circles, its periodic swing, the other end of stirring rod and the contact of the rubble of accumulation are also followed to the stirring rod to play the effect of stirring, with this work efficiency who improves the stone crusher, prevent the jam of mud conveying pipe mouth department.