The purpose of this study is to formulate a model of the ma'danaka cultural identity of the Bajau tribe in the midst of the heterogeneity of cross-cultural communication. The activity of preserving culture as a system has various interrelated elements with parts of the life system in the community. Culture as an embryo that emerges from society. Culture is born into a society where all human actions are culture. Preserving culture besides having an ideological content is a step to strengthen culture, history and identity. The cross-cultural communication that exists between the Bajau and immigrant tribes is one of the diversity that exists in Bontang Kuala. The Bajau tribe, which is known as a sea tribe, is able to carry out good social interactions with various immigrant tribes. In this study, the main theory used is the theory of social interaction, social change, and social behavior. Meanwhile, the supporting theories are the theory of social change, social structure theory, conflict theory, and functional structure theory. Meanwhile, the method of this research is qualitative analysis using data analysis techniques of Milles and Hubeman involving 7 informants to obtain the data. The results of this study include: a) social interaction is built on heterogeneity and differences in customary values, social behavior created by collaborating the behavior of land and sea and the entry of Islam changes patterns of social interaction and forms new social behavior. b) Two-way communication patterns are carried out for cultural exchange and acceptance. Tejasi changes in the living traditions, livelihood, language of discussion and dominant rituals of the Bajau tribe. As well as intercultural communication can determine, maintain, develop culture so that it can be passed on to the next generation. c) Behavioral tendencies in interpreting customary values: behavior that adopts the basic values ??of the Bajau tribe such as respecting the sea. brotherhood values, sharing goods and changing goods Positive and negative impacts. Positive impacts: strengthening values, strengthening tribal existence, increasing tolerance, and integrating socio-cultural values. Negative impacts: rejection of values, ethnic disintegration, message distortion, horizontal conflict. Ma'danaka in social interaction contributes positively and contributes to the order and peace of the life of the Bajau and other tribes.