In recent years, the Build-Operate-Transfer (BOT) project has become a widespread mode for infrastructure construction. The BOT project is promoted to alleviate the government financial pressure and lead in efficiency of the private sector. There were a lot of large constructions to adopt BOT model, such as Taiwan High Speed Rail, Kaohsiung Rapid Transit System, and so forth. Self-liquidating ratio (SLR) is one of the most important indicators in evaluating a BOT project. Since the cash flow structures are different between BOT projects and projects financed solely by government, the original SLR formula is not perfectly suitable. Therefore, this study revises the SLR formula, and tries to use the new definition to construct a financial-decision model for the government and concession company. When the government administration and the concession company negotiate a concession agreement, they have to determine the investment proportion and royalty. However, traditional evaluation model, such as Net-Present Value Method, Internal Rate of Return Method, are rarely focus on the theme. As a result, there is not a appropriate standard to use. This study combines cash flow concept and linear programming method to construct financial-decision models for both sides. We expect to look for a bargain space of investment proportion and royalty. With the bargain space, the participants of BOT project can make a better investment decision, and reduce the wrong policy which may lead the waste of social resources.