A proper concession term is the key to success in the contractual negotiation for BOT scheme. This paper introduces a profitable operational period, and set up an game model between the government and the project company, in order to analysis the interrelations between the optimal strategies of the government and the optimal strategy of the project company in BOT schemes. By employing game theory, their optimal strategies are brought forward respectively. The results can provide the government and the project company with a decision-making support in BOT scheme.