Abstract: The body tensile strengh of the centrifugal-casting gray cast iron pipes treated with RE can be improved to 25.9%(pouring of ladle) or 42.4% (spraying process), while their average values are 214N/mm², and 242N/mm² respectively. Both surpass the (ISO13-78) specification (180N/mm²) and reach the requirement of metal mold centrifugal-casting gray cast iron pipes. The cast iron pipe thickness is 2.2mm(14.1%) thinner than the international standard.