Locking fastening device and electric wrench thereof

The invention provides a locking fastening device and an electric wrench thereof. The locking fastening device comprises a locking shell, a locking screw and a spring. The locking shell is composed of a conical face, a hexagonal face and a flange. The conical face is used for eliminating the displacement deviation and the angular deviation of the locking fastening device and an operation tool. The hexagonal face is used for eliminating operation counterforce. The electric wrench of the locking fastening device comprises a shell, a driving assembly, a reversing assembly and an output assembly. The shell supports all parts of the electric wrench. The driving assembly transmits torque to the output assembly through the reversing assembly so as to achieve a screwing function on the locking fastening device. By the adoption of the disclosed scheme, the beneficial effects that counterforce transmission is avoided, the wrench can axially move automatically in the axial direction of the screw, torque can be output at multiple angles, and the requirement for operation space is low are achieved.