Abstract: The relationship between rights and obligations is an important indicator and internal yardstick to measure social justice. A truly just society realizes the unity of rights and obligations between people. The transcendence of Marx's concept of social justice lies in that it reveals the hypocrisy of the unity of rights and obligations in capitalist society, and clarifies the possibility and necessity of the unity of rights and obligations in Communist society. It provides important practical guidance for the construction of a justice society in China.