Why does it always overrun the budget? Those who engage in construction engineering practice, including budgeting, contracting and construction site management, often experience additional project budgets. The business operator of the construction company will feel the pain as flesh- like when project budgets were overspent. Relating issues have not been researched to the bottom yet till now. Such as: How serious they are for overrun? What caused it? How much it will impact? And could it be comprehended then find ways to resolve? And so on. The research methods employed in this study are through questionnaire survey, interviews with professionals and the case study to collect data as the foundation of analysis and to explore various problems about discrepancies and links between budgeting and completion of settlement. According to findings of this study, the researcher will offer some suggestions to relating engineers and business operators.