Abstract: Social justice is the value core of modern morality. From the perspective of Marxism， social justice is interpretable. It has the historical and hierarchical nature which is suitable for the mode of production. It also acts as a normative tool with the liberation of human being as the main theme， and is used to evaluate specific mode of production and social system. At the same time， it shows a theoretical direction which uses institutional criticism and institutional revolution as the way of social justice realization. Social justice contains ethical attributes， and is associated with the institutional and value background of moral occurrence. It is the primary virtue of social system and individual citizens， and is presented as a series of normative moral entries. The main directions of collective moral construction include strengthening the construction of social justice and institutional justice to guarantee moral justice， abandoning the “unreal collective” and moving towards the “real collective” based on the value of human liberation， and determining the boundaries of collective interests and affirming the reality of individual interests and its necessity to collective interests.

Key words: social justice; morality; Marxism; institutional justice; collective morality