The application discloses a universal joint assembly. The universal joint assembly, includes a base, two clamping members, a ball shaft, and a locking member. The base has an accommodating groove, a first opening and a second opening disposed opposite to the first opening. The clamping member is disposed inside the accommodating groove. Each of the two clamping members includes a bearing portion, a fulcrum portion, and a clamping portion. An adjustable space exists between an outer side of the bearing portion and an inner wall of the accommodating groove. The locking member presses the ball shaft and the bearing portion. The clamping member take a position where the fulcrum portion contacts the inner wall as a fulcrum, so that the clamping portion moves toward the ball shaft and clamps the ball shaft.