Aiming at the challenges of traditional BIM-based construction management platforms, including data complexity, unclear management priorities, and difficulties in data permission control, this paper proposes a "construction-management separation" BIM information management platform system for metro construction. The research demonstrates that this system effectively addresses the limitations of conventional single-platform BIM construction management. In the platform architecture, the construction management platform employs key technologies such as multi-model integration, automatic information collection, and digitalized workflows, achieving automated business data collection, integrated supervision information, and automated office processes. This significantly enhances the efficiency of construction data management in metro projects. Leveraging the operational data from the construction management platform, the comprehensive monitoring platform utilizes big data extraction, analysis, and visualization technologies to refine key metrics, successfully resolving issues such as unclear management focus, non-targeted measures, and irregular on-site control caused by data overload. Practical application in Guangzhou Metro Line 11 project verifies the feasibility of this BIM-based metro construction information management system proposed in this study.