This paper proposes a transformative approach to engineering cost management by developing a data-driven, object-oriented platform that integrates data middle platform technology with BIM and digital design methods. Through unifying design objects with cost objects, the platform allows for automated cost calculations, real-time tracking, and intelligent decision-making across the dimensions of quality control, schedule management, and cost optimization. Emphasizing sustainability, the platform includes modules for low-carbon economic assessments and aligns with green engineering standards. Case studies demonstrate improvements in cost accuracy and project management efficiency while reducing manual workload. Successful adoption of this approach depends on standardized design input, robust data governance, and compatibility with existing cost standards, presenting challenges and opportunities for advancing engineering digitalization in line with environmental goals.