Based on the idea of real option, this paper uses BS model to evaluate the rationality and profitability of canceled expressway toll by using the construction of Ba’nan expressway as an example, we find that the real option theory well explains the rationcelity of the cancelled highway toll, and even without toll, the combination option financing ways used in highway construction will bring about great profit margins, which ensures the highway construction funds and also does good to the economy, and which avoids returning the loan by the toll and also achieves a win-win situation.