This study examines project cost overruns in project management with a focus on S3 Project at Kanshanshi Mine. The main objectives were to identify types of cost overruns, assess their effects on project management, and evaluate the effectiveness of cost strategies. A descriptive research design was employed, with a sample of 50 respondents. Findings review that poor project planning, inefficient resource allocation and scope changes are significant causes of cost overruns. Inaccurate cost estimation and inadequate risk management contributes to project delays and budget issues. The study recommends thorough project planning, efficient resource allocation, and effective risk management practices to mitigate cost overruns. Additionally, fostering stakeholder collaboration and using metrics like Earned Value Management (EVM), Cost Performance Index (CPI), and Schedule Performance Index (SPI) can enhance project cost strategy success.