Tower crane

The utility model relates to the field of building crane equipment, in particular to a tower crane which comprises a balance arm, a tower head, an arm root section and a variable-amplitude oil cylinder. The upper part of the tower head is connected with the upper joint of the arm root section; one end of the tower head lower part is detachably connected with the lower joint of the arm root section; one end of the variable-amplitude oil cylinder is connected with one side, far away from the tower head, of the arm root section, and the other end of the variable-amplitude oil cylinder is connected with the lower part of the tower head; and the balance arm is connected with the other end, far away from the arm root section, of the lower part of the tower head. Due to the fact that the balance arm and the arm root section are not directly connected into a whole, when the variable-amplitude oil cylinder works, only the cargo boom comprising the arm root section can do variable-amplitude motion, the balance arm does