The double eccentric butterfly valve with a thick and large cross section exists the unstable and the unqualified problems in property index by using the 3 to 8 light rare earths nodularizer.The change of structure and mechanical properties of the casting after pouring control were analyzed with applying the yttrium base heavy rare earths nodularizer（TZ-3 A）as well as adjusting the content of C and Si elements with strictly controlling the content of alloying elements.The spheroidizing and the inoculation treatment were performed according to the original technology.The problems such as spheroidizing fading in the heart part of the double eccentric butterfly valve

graphite ball coarseness and graphite flowering were solved.The results show that the tensile strength and the elongation of the valve body reach more than 450 MPa and 10%

respectively

meeting the requirements of the customers.