Abstract: The level of urbanization has continuously improved,which expands the need of the urban environment infrastructure.The BOT model can change the situation of insufficient investment of environmental infrastructure from the government.The BOT model uncertainty increases the difficulty of the decision-making of investors.Real option model can better reflect the influence of uncertainties to environmental infrastructure value of BOT projects,which is conducive to investors to make a decision.The paper identifies urban environmental infrastructure expansion options and applies Black-Scholse Option Pricing Model to calculate the options value of the BOT project.Through specific cases,the paper analyzes the decision-making process of investors.

Key words: environment infrastructure, real option, BOT project, decision-making