This paper focuses on the evolution of organizational communication theory in the social media field and the optimization that information dissemination has on the traditional organizational structure. To investigate Twitter accounts’ dynamic cooperation and coordination mechanism in major military activities，this paper studies on the structural relationship of 113 Twitter-certified accounts and the information dissemination and interaction of US military’s Twitter accounts in the Pacific Rim military exercises of 2016，based on Social Network Analysis. It found that all the US military’s Twitter accounts release information selectively，which is mainly decided by their level of involvement in the events. Their interaction model features a typical dynamic central radiation. Moreover，the US military not only established verified Twitter accounts as official information dissemination channels，but also it opened a variety of unofficial Twitter accounts whose influence is even higher than that of the former.