Abstract: This paper provides a framework of symmetric duopoly option game and discusses the optimal strategy decision problems in corporate investment under the stochastic conditions of both project demand and operation cost which are correlative. We analyze especially the equilibrium rules of optimal strategy and its conditions and make a comparative static analysis to the influence of parameters to optimal thresholds after educing investment value function and optimal investment threshold. At last,we draw some significant conclusions and make economic explanations.

Key words: investment decision, real options, option games, duopoly