Family is not only the starting point of personal social relations, but also an important unit to study social changes. As the primary condition for maintaining human survival and reproduction and an important embodiment of family functions, infant feeding is undoubtedly an important perspective to study the changes of family structure in modern China. In modern China, the new concept of milk nursery and its practical effect led to the change of family structure and parentchild relationship. On the one hand, the widespread use of dairy substitutes in cities had become a catalyst for the transformation process from traditional clanlike big families to nuclear families, which promoted the private domain of families; on the other hand, the use of formula improved the survival rate of infants in urban middleclass families, and put forward new requirements for fatherhood and motherhood. Professional formula offered convenience for mothers to break away from the natural motherhood of breastfeeding, enabled professional women to quickly end their lactation and go back to social production, and also enabled new mothers to shift from “nurturing” to focusing on educating infants. Standardized formula also enabled men to participate in and make decisions on infant feeding, which provides an opportunity to shape a more intimate relationship between father and son/daughter. This personal emotion that pays more attention to parentchild relationship is regarded as the embodiment of modern individualism in the private field. Investigating the changes of breastfeeding and milk replacer is helpful to grasp the structural transformation of family and society from the changes of daily life, and to understand the transformation of parentchild relationship and personal emotion in modern China.