Abstract: The Φ298.5 mm×70 mm large-sized heavy-wall, S355J2H seamless steel tube for port machinery service is successfully developed via studies on the chemical composition design, the melting process, the rolling process and normalization treatment process.Results from relevant analysis and inspections demonstrate that the said seamless steel tube as produced with the process series of"EAF+LF+VD+forging+pipe-rolling with Φ508 mm pilger mill+normalization treatment" is in possession of clean steel quality, high strength, excellent low temperature impact toughness, homogenous post-normalization properties and structure, and yield ratio under 0.70 in any case.Quality level of the tube is equal to that of the similar product as imported from abroad.