Joint, fastening device with joint and assembly of joint and fastening device

The utility model provides a joint, a fastening device with the joint and an assembly of the joint and the fastening device. The joint comprises a ball seat, an inner ball shell, a pivot ball and a shaft rod. The ball seat comprises a rotating axis. The inner ball shell is rotatably arranged in the ball seat and jointed with the ball seat, and also capable of rotating around the rotating axis relatively to the ball seat. The pivot ball is rotatably arranged in the inner ball shell and jointed with the inner ball shell, and comprises a self-spinning axis perpendicular to the rotating axis. The pivot ball is capable of driving the inner ball shell to rotate together around the self-spinning axis. One end of the shaft rod is connected to the pivot ball, while the other end of the shaft rod extends out of the ball seat from the self-spinning axis; the shaft rod is capable of driving the pivot ball to rotate around the self-spinning axis relatively to the inner ball shell, and also capable of driving the pivot ball and the inner ball shell to rotate together around the rotating axis. As a result, the shaft rod is capable of rotating in multiple directions relatively to the ball seat.