From a lower social level, "street graffiti" is no longer a simple graffiti by hooligans, or a way to improve personal popularity by scribbling signatures and inscriptions everywhere. It has developed into a vivid and rich visual art form, which can be clearly seen on the walls of many big cities in Europe and America, especially in the subway in new york. In the 1970s and 1980s, a large number of carefully designed and professionally painted graphics often appeared in new york subway. These various graphics come from personal imagination or popular culture. From 1970 to 1980, we can see the influence of Latin American mural art, especially Mexican mural art.