Nowadays, "music" is an influential medium and a culturally consumable commodity. Music creates effective and lasting spiritual and psychological effects due to the auditory attractions and psychological incitation. In recent years, "rap" music, as a media instrument of the "HIP HOP" subculture, has attracted many fans, who act in contradiction with the dominant culture of societies or the relationsHIP between two is comprising tension, and in this sense, it is called "underground music". This type of music tries to excite and attract the most ordinary people of the society with the most street words(slangs). This type of media has different types in its texts and hypertexts and provides different functions for its listeners. This article tries to answer this question: "What are the media functions of Persian underground rap music in the 80s and 90s? With what themes does it promote itself? To get the answer, we used the qualitative method of theme analysis, and the lyrics of the four famous rap singers (UnderGround) in the last 20 years, which were about 92 songs and 6574 words, were coded and analyzed. We conclude that the functional themes of these texts are more about awareness, information, unconscious and conscious transmission of culture, sense of community and social cohesion.