The invention discloses a manufacturing method for an automobile variable-strength thermally formed part. The manufacturing method comprises the following steps: S1, selecting steel for thermal forming as a hard region material; and S2, selecting a soft region material and controlling the thickness of the soft region material to be 0.7mm-2.0mm, wherein chemical components of the soft region material are as follows: less than or equal to 0.10% of C, less than or equal to 0.1% of Si, 0.5-1.0% of Mn, and less than or equal to 0.020% of P. According to the manufacturing method for the automobile variable-strength thermally formed part disclosed by the invention, the existing hot stamping equipment does not need to improve or additionally arrange, and a thermal forming mould does not need to re-design, so that mould development cost is reduced, the service life of the mould is prolonged, process stability of production is good, the soft region material cost is low, production is easy, performance stability after welding is good, and welding seam quality is high; a transition region position, width and part soft hard region performance are relatively good in consistency; and parts with different strength grades can be obtained by selecting different hard region materials (1500MPa or 1800MPa), so that parts obtained by the method are good in moulded surface dimension.