35CrMo ultrathick wall seamless tubes were prepared after being hot rolled from a forged 305 mm×305 mm square blank using a Φ216 mm Pilger periodic mill. Tubes with 215 mm outer diameter, thickness of approximately 725 mm, and a 297 diameterwall ratio were obtained. Two sets of tubes were prepared after analyzing the reasons for high eccentricity and rolling parameters. The uniformity of rolling temperature, piercing quality and roll pass were considered during the procedure. The geometry size, microstructure and mechanical properties were measured. It is found that the tubes meet the technical requirements.