Abstract: To address the problems of insufficient multi-source data integration and delayed real-time decision-making in the digital transformation of railway freight wagons, this paper constructed a digital index monitoring system for railway freight wagons. The system covered seven business domains including professional quality control and safety monitoring of these wagons, forming 74 quantitative indicators and a three-level early warning mechanism. By integrating the Fuzzy Analytic Hierarchy Process (FAHP) and Grey Relation Analysis (GRA), the paper optimized the dynamic weights of indicators, and proposed a Health Index (HI) evaluation model integrating Z-Score standardization and trend penalty factors, thereby improving the accuracy of state discrimination. The pilot application in China Railway Beijing Group Co., Ltd. shows that this system effectively solves the problems of delayed manual reports and information silos, improves the efficiency of freight wagon management, and provides an extensible technical path and decision-making paradigm for the digital transformation of railway freight wagons.