According to Ostwald ripening theory of second phases in dilute solution, the effect of relative content of sulfur and manganese in steel on controlled element of the Ostwald ripening process of manganese sulfide has been theoretically analyzed and calculated. The calculating results show that the controlled element to be sulfur or manganese is mainly determined by whether (Mn-R·S) being greater than C value-D Mn-γRD S-γ10 5.02-11625/T(D S-γD Mn-γ-1) during the Ostwald ripening process of man...