In recent years, the competition for comprehensive national power based on resources has become increasingly fierce, and the optimal layout and rational allocation of mineral resources on a global scale become the primary task in implementing the "going out" strategy for mineral resources. In this paper, the cost classification system is analyzed corresponding to the definition (maturity) level and the technical deliverables of mining projects at different development stages. The typical cost estimation accuracy corresponding to different cost classification is studied to provide a basis for stakeholders to form a common understanding of cost estimation results and accuracy.