The invention belongs to the technical field of forming and relates to a torsion beam preparation method which comprises the steps of pipe bending, performing, hydraulic forming and thermal treatment. The pipe is prepared from the following chemical components in parts by weight: 0.22-0.24% of C, 0.22-0.25% of Si, 1.22-1.25% of Mn, 0.005-0.008% of P, 0.001-0.002% of S, 0.030-0.049% of Al, 0.003-0.0045% of B, 0.06-0.08% of Ti, 0.05-0.10% of Cr, 0.15-0.2% of Mo, 0.15-0.2% of Ni, less than or equal to 0.05% of Cu, 0.1-0.2% of Co, and the balance of Fe. According to the invention, the pipe has good elongation in a forming state so as to meet a forming requirement; while after material forming is completed, the pipe has relatively high tensile strength through thermal treatment.