Abstract: A number of shortcomings stay with the production of the cold-processed 300 Series austenitic stainless steel pipes as sized under Φ89 mm，namely，rather long manufacturing process flow and production cycle，low output，low yield，high operational costs and environment-contaminating pickling operation，etc.Addressing such problems，based on study on the deformation process，the process of hot rolling（piercing+sizing）plus in-line water cooling is designed and developed to produce seamless stainless steel blank pipes sized under Φ89 mm.Results from inspections of and tests to the pipes as made with the above mentioned process show that their dimensions are close to the finished cold-rolled pipes.It is concluded that the said manufacturing process is capable of reducing intermediate cold-rolling（drawing）passes，simplifying the process flow，shortening the production cycle，and increasing the yield，being remarkably economic.