The utility model discloses a device for protecting chopper transmission of a cigarette making machine. The device comprises a main shaft, a clutch and a limit switch; a belt wheel for inputting power is mounted on the clutch through a screw; the clutch is connected with the main shaft through a key and fixed on the main shaft through a retaining ring; the belt wheel is mounted on the main shaft through a bearing; the limit switch is mounted on a bracket below the clutch; a contact of the limit switch is clamped in a groove of a torque sensor of the clutch; and the clearance between the groove wall of the torque sensor and the contact of the limit switch is well adjusted according to a certain requirement, so as to ensure the movement sensitivity. The device has the advantages that when a large nonmetal foreign body in cut tobacco clamps a chopper disc and the instant impact is produced, the power supply can be cut off in time and the machine can be halted, thereby avoiding a gear in a transmission chain of the chopper from being badly damaged because of collision, and reducing unnecessary property loss and maintenance trouble for customers. The device is applicable to all types of cigarette making machines such as ZJ17, ZJ112, and the like.