A universal joint assembly, comprising: a base, having an accommodating groove, a first opening and a second opening opposite to the first opening, wherein the accommodating groove is connected to the first opening and the second opening; a ball shaft; and a locking member, entering the accommodating groove through the first opening and pressing the ball shaft, characterized, in that the universal joint assembly further comprising: two clamping members, disposed inside the accommodating groove, wherein each of the two clamping members comprises a bearing portion, a fulcrum portion, and a clamping portion, the bearing portion is close to the first opening, an adjustable space exists between an outer side of the bearing portion and an inner wall of the accommodating groove, the fulcrum portion is located between the bearing portion and the clamping portion, the fulcrum portion is in contact with the inner wall, and the clamping portion is close to the second opening and is in contact with the inner wall; wherein the ball shaft is disposed between the two clamping members; and the locking member presses the bearing portion, wherein the bearing portion moves toward the inner wall in the adjustable space, so that the two clamping members take a position where the fulcrum portion contacts the inner wall as a fulcrum and the clamping portion moves toward the ball shaft to clamp the ball shaft. a base, having an accommodating groove, a first opening and a second opening opposite to the first opening, wherein the accommodating groove is connected to the first opening and the second opening; a ball shaft; and a locking member, entering the accommodating groove through the first opening and pressing the ball shaft, characterized, in that the universal joint assembly further comprising: two clamping members, disposed inside the accommodating groove, wherein each of the two clamping members comprises a bearing portion, a fulcrum portion, and a clamping portion, the bearing portion is close to the first opening, an adjustable space exists between an outer side of the bearing portion and an inner wall of the accommodating groove, the fulcrum portion is located between the bearing portion and the clamping portion, the fulcrum portion is in contact with the inner wall, and the clamping portion is close to the second opening and is in contact with the inner wall; wherein the ball shaft is disposed between the two clamping members; and the locking member presses the bearing portion, wherein the bearing portion moves toward the inner wall in the adjustable space, so that the two clamping members take a position where the fulcrum portion contacts the inner wall as a fulcrum and the clamping portion moves toward the ball shaft to clamp the ball shaft. two clamping members, disposed inside the accommodating groove, wherein each of the two clamping members comprises a bearing portion, a fulcrum portion, and a clamping portion, the bearing portion is close to the first opening, an adjustable space exists between an outer side of the bearing portion and an inner wall of the accommodating groove, the fulcrum portion is located between the bearing portion and the clamping portion, the fulcrum portion is in contact with the inner wall, and the clamping portion is close to the second opening and is in contact with the inner wall; wherein the ball shaft is disposed between the two clamping members; and the locking member presses the bearing portion, wherein the bearing portion moves toward the inner wall in the adjustable space, so that the two clamping members take a position where the fulcrum portion contacts the inner wall as a fulcrum and the clamping portion moves toward the ball shaft to clamp the ball shaft.