The invention discloses a wrist ball and a shell thereof. The wrist ball comprises the shell and a rotating body, wherein the shell is provided with a buffering part; the buffering part is provided with a rail part and a buffering body; the buffering body corresponds to the rail part in position; the rotating body comprises a ferrule and a rotating ball; the ferrule is positioned in the shell, and is arranged on the rail part in a sliding way; the rotating ball comprises a ball body and a shaft body; the ball body is positioned in the shell; the shaft body penetrates through the ball body, and the two opposite ends of the shaft body are pivoted to the ferrule respectively in a way of rotating relative to the ferrule. According to the wrist ball and the shell thereof disclosed by the invention, the rail part can be used for driving the shaft body and the ball body to move together according to the elastic buffering deformation capability of the buffering part, so that collision stress is prevented from being concentrated on a joint between a pivoting segment and a carrying segment. The collision force carried by the shaft body can be shared by means of the elastic buffering deformation capability of the buffering part, so that the shaft body is prevented from being bent or fractured due to collision.