In order to improve the accuracy and operational efficiency of construction cost management and comply with the trend of digital development in the construction industry, this article starts with an overview of big data technology and constructs a construction cost management system based on big data technology. The aim is to effectively integrate various types of construction cost related data and rely on the analysis and mining capabilities of big data to achieve accurate prediction and dynamic monitoring of construction costs. Through practical verification, the system can optimize resource allocation, reduce cost deviation, significantly enhance the scientificity and controllability of cost management, and provide useful reference and inspiration for cost management work in the construction industry.