[en] Primary piping steel of Z3CN20-09M for nuclear power plant is melted by combination of electric furnace and AOD furnace, ferrite content of Z3CN20-09M are adjusted based on the compute result of Scharffler. Measures by enlarging the wall thickness of shell, decreasing inside diameter of the baffle, selecting greater g value and increasing machining allowances of internal surface, etc, in centrifugal casting process, sample of primary piping are cast. Measure results show that various performance of sample of primary piping the needs of RCC-M are without exception meet