Abstract: Traditional methods often rely on standardized process control or cost allocation principles to manage project costs, but these methods often result in significant deviations and struggle to effectively address the challenges of high costs and low resource utilization in large-scale replacements. To tackle these issues, a study was conducted on a cost control method for domestic terminal county-wide replacement projects that considers resource optimization. The study begins by breaking down the project cost structure to identify key cost elements such as hardware, software, labor, and operations and maintenance. By considering the specific conditions of the county and the project stages, the study conducts resource demand forecasts to accurately estimate resource needs. Based on these forecasts, a dynamic control system for project costs throughout the entire lifecycle is established, focusing on resource optimization to achieve real-time resource allocation and dynamic cost control. Analysis of the cost control results shows that this method has significantly reduced the total lifecycle costs, with all standardized cost deviations being positive. The actual costs incurred during each construction phase were lower than the budgeted costs, effectively controlling the project costs. Additionally, the actual cost curve remained consistently low, and the earned value curve did not exceed the planned cost curve, indicating that the project's actual costs were below the budgeted costs and within the planned cost range, achieving the ultimate goal of cost savings.