Abstract: Based on communication model in information theory,a game theoretical model is developed.And different definitions of strategic entropy for different kind of games are presented respectively. Then we prove that a mixed strategy with maximum entropy is sufficient and necessary condition for Nash equilibrium,which demonstrates that Nash equilibrium is the equilibrium not only of benefits but also of information. Based on the basic theorem we presented,the method of achieving and refining Nash equilibrium is presented by the end.

Key words: information theory, game theory, strategic entropy, maximum entropy principle