Border areas are inhabited by multiple ethnic groups and serve as key regions for cross-border exchanges. There exists a close and interactive correlation between language use and cultural identity, which is closely linked to border stability and ethnic communication. Taking cross-border ethnic groups in border areas as the research object, this study focuses on exploring the influencing mechanism of language-cultural identity. The research findings show that family language environment, daily social interaction, and school education guidance are the main factors affecting mother tongue identity, common language cognition, and cultural heterogeneity cognition. Language is not only a tool of communication but also an important symbol of cultural identity; in turn, cultural identity also influences the selection and inheritance of language. The two interact and promote each other at the family, community, school, and social levels, contributing to the construction of a stable psychological identity structure. This study further puts forward effective ways to enhance the language-cultural identity of cross-border ethnic groups in border areas, aiming to provide a theoretical basis and practical guidance for ethnic communication, cultural integration, and social stability in border areas.