With socioeconomic development, social justice has gradually become a focus topic. Not only is justice reflected in social phenomena, but also it plays an important role in the ecosystem. By constructing a capital exchange agent-based model and simulating the dynamic process of social wealth distribution, this paper observes the changes of capital exchange entropy to explain the entropy increase theory. Furthermore, the maximum entropy of the final state differs from system to system, ecological justice of the system can by evaluated vertically or horizontally based on entropy increase theory and the Maximum Entropy Index. The constructed entropy model of capital exchange can prove the maximum entropy theory. Meanwhile, the phenomena of wealth concentration would totally give the right of choice to the affluent group, harming sustainable development.