The success of each ethnic culture and between religions to coexist in their cultural differences is another fact that must be collected and without denying the potential for conflict in heterogeneous societies. Because it is not conflict that is an important issue in the relationship between ethnic and religion, but also the basis of social culture that allows assimilation to occur. This paper examines the patterns of intercultural communication in building harmonization of heterogeneous communities in the city of Mataram. This research is a field research using qualitative which has the purpose of documenting, evaluating and re-interpreting the world view, the value of meaning and general characteristics of a person or community group about life events, discussions and discussions involving other researches. In this study it was found that the pattern of intercultural communication in building heterogeneous community harmonization in the city of Mataram was very effective, of course it was related to the people who were very active in communicating and public openness in the conversation so far and did not choose only for certain needs. Effective communication patterns are carried out through dialogue, social interaction and talks between fellow citizens in the city of Mataram in everyday life.