Abstract: To address the shortcomings of traditional earned value management (EVM) in cost control and optimization, this paper proposes an improved EVM method integrated with BIM5D technology to develop a comprehensive cost warning system; the system leverages the BIM5D platform to consolidate, filter, and analyze multi-source data, and through custom-developed programs, it retrieves and calculates data from the BIM5D platform in real-time, automatically detecting and analyzing cost variances and issuing warnings; through an empirical analysis of a school cafeteria project, the feasibility and effectiveness of this warning system have been validated, with the results showing that the system can promptly and effectively identify and assess cost variances, alerting project managers through an automatic warning mechanism to handle deviations in a timely manner, thus enabling efficient dynamic cost control, and providing advanced technical support for construction cost management in the building industry, promoting its digital transformation and development.