Abstract: Based on the pass parameters of the existing Mini-MPM mandrel mill, the 194 mm series passes are developed according to the distribution method of top elongation coefficient, and in turn the piercer plug is re-designed.Statistics is conducted, covering the yield and wall thickness data of the Φ139.7 mm×7.72 mm oil casing and the Φ178 mm×9 mm axle pipe as produced with the 194 mm series passes.It is regarded via the analysis that the said 194 mm series passes are practicable, and production of the above mentioned pipes with the two sizes as rolled with the passes features consistent product quality and high yield.