The invention discloses a pulling force adjusting bolt which comprises an upper bolt and a lower bolt, wherein a connecting thread is formed in the upper part of the upper bolt; a bulged positioning key is arranged at the lower part of the upper bolt; a connecting thread is formed in the lower part of the lower bolt; adjusting grooves are formed in the upper part of the lower bolt at equal intervals in the axial direction; the positioning key of the upper bolt can adjust positions in the adjusting grooves at will; the adjusting grooves are formed in the upper part of the lower bolt in the radial direction; the upper part of the lower bolt is hollow tubular; the adjusting grooves formed between the upper bolt and the lower bolt are utilized, the adjusting bolt is adopted to connect the interval between every two adjacent adjusting grooves and to adjust heights of a nut and the bolt so as to realize high-precision pulling force adjustment of the bolt; and a ring lock is arranged to ensure that the positioning key of the bolt is prevented from falling off to cause an accident after the bolt adjusts the positions.