Abstract: Pass design is the core technology of the MPM,and determination of the pass parameters is directly related to consistency of rolling process,product dimensional tolerances,surface quality and the variation of the rolling energetic parameters,etc. Described in the paper are the efforts in developing pass design of the Φ159 mm MPM by Seamless Steel Tube Plant,Angang Xingangtie(New Iron & Steel)Co.,Ltd. in a bid to effectively using the mandrels,expand the product size range and improve tube dimensional accuracies. Thanks to proper modification of the MPM math model as introduced from Germany SMS Meer GmbH,the rolling schedule with the passes as designed has been operated successfully to produce high quality tubes.