Any application software must access to the operating system software to achieve its function.This paper analyzes the optimal information disclosure of software with access by game theory.Disclosing interface information will result in two kinds of effect.On the one hand it will introduce competition.On the other hand it can raise the consumer appreciation.So there is a trade-off for the operation system(OS) firm.We build a game model and conclude that OS firm should disclose all the interface information completely.And we also analyze the optimal pricing strategy of OS and application software.