Manufacturing process capable of improving stability of torsion bar spring

The invention relates to a manufacturing process capable of improving stability of a torsion bar spring. The manufacturing process sequentially comprises the following steps: a blanking process, a rough turning process, a thermal treatment process, a precision grinding process and a linear cutting process, wherein a heating pre-twisting process and a thermal aging treatment process are carried out between the precision grinding process and the linear cutting process. According to the manufacturing process, heating pre-twisting is carried out by three times for enabling a twisting angle of the torsion bar spring to be 90-100 degrees, and then, the temperature is slowly raised to 110-120 DEG C and kept for two hours, so that activeness of molecules inside the torsion bar spring is increased, realignment of crystalline grains is facilitated, compactness of molecules on the surface of the torsion bar spring is increased, and acting force among the molecules is improved, thereby achieving the purposes of reducing a residual deformation angle and improving a torque value; the thermal aging treatment process is carried out, and the torsion bar spring is placed into a thermal ageing furnace in a no-load mode, slowly raised to 180-200 DEG C and kept for two hours, so that unstable residual stress inside the heated and pre-twisted torsion bar spring can be removed, and therefore, the stability and the torque of the torsion bar spring are improved.