Social fintech envelopes social networks within financial concepts and tokenization, and its complexity requires innovative technological solutions and theories to meet user demands and achieve sustainability. The first thing is the mapping principle between physical real society and virtual digital world. Therefore, this article uses online game <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Nova Empire</i> as a case study, aiming at using multiplex networks to understand the physical–digital structural consistency for social fintech sustainable development. Specifically, we first proposed an eight-layer multiplex network to model the complex gaming behaviors for players. Furthermore, we analyze the structural properties and social balance of the social networks. Particularly, the layers in multiplex networks composed of positive behaviors has higher reciprocity than the layers composed of negative behaviors, the out-degree distributions of nodes in the layers composed of negative behaviors basically conform to the power-law distribution, and the small-world phenomenon is also common in virtual game. The experimental results prove the structural consistency between physical and digital. Finally, new solutions for social fintech and mobile Internet industry are proposed based on the mapping principle, which will provide technical supports for the realization of sustainable development and social responsibility of social fintech.