Abstract: We presented the notion of strategic entropy at the beginning of this paper and discussed the relationship between the maximum strategic entropy and Nash Equilibria. Then we employed the maximum entropy inference to estimate mixed Nash equilibrium and got the same results as classical methods. And we demonstrated that strategic entropy under Nash Equilibrium is the maximum entropy, which produced an information-theoretic explanation of game theory and a new method to calculate mixed Nash equilibrium. A practical example ended our paper to confirm the feasibility and validity.