Abstract: To solve problems such as low service life of hot tools, high consumption and unstable product quality of 238 mm series passes of the piercing mill for Ф180 mm Mini-MPM plant, the passes and hot tools of the piercing mill are optimized, and Ф245 mm billets are adopted to replace Ф230 mm billets.The practical operation shows that the new 238 mm series passes and hot tools are reasonably designed, and when Ф230 mm billets are replaced by Ф245 mm billets, both the dimension accuracy and inner/outer surface quality of the rolled products are up to the contract requirements.