National language security is a key component of holistic national security, yet existing researches have generally failed to conduct an in-depth exploration of these issues and their characteristics. To address this gap, this paper first clarifies the definition and basic scope of national language security, then takes “National Security and Defence Dataset” as the research object to comprehensively explore the characteristics and develops a model to address national language security issues. The study finds that military language competence and the implementation of official language policies are among the core concerns of national language security. These issues collectively form a complex model encompassing status planning, corpus planning, acquisition planning, and discourse planning. The exploration of national language security issues and model construction may help provide theoretical insights and practical references to improve holistic national language security capabilities.