The invention discloses a regulating device of line straightening machine, which comprises an upright regulating screw rod, a handwheel arranged on the top end of the regulating screw rod, a nut connected between the regulating screw rod and the handwheel, a frame sleeved on the lower part of the regulating screw rod and formed by level upper and lower plates and an upright riser, wherein the riser is connected with the lower parts of the upper and lower plates and forms the frame, the lower part of the regulating screw rod is in the frame, an upright leader is also arranged in the frame, theleader and the regulating screw rod are respectively arranged on the left and right, a transverse regulating block is sleeved on the regulating screw rod and the leader, one end of the regulating screw rod is outside the frame and is connected with a transverse shaft which is sleeved with a V belt wheel, and a bearing is arranged between the V belt wheel and the shaft. The invention has the advantages of high regulating speed, high controlling stability, time and force conservation, one-time regulating and fixation, and big regulating range.