Persian letters in the form of abstract forms and abstraction after passing the coding period are the main basis of visual communication in the field of typography and design of written signs. The design of written logos as a visual identifier and visual identity of an organization, product, service and brand is of prime importance in visual communication. Letters as the call of the image with two approaches "linguistic structure" and "aesthetic structure" form the main form of written signs and these two approaches complement each other. Investigating the role of Persian letters in the creation of cultural written signs of the solar 50s (with a case study of qualitative and statistical works) is the main subject of this research. The method of this research is descriptive-analytical and the method of collecting information sources is library and internet. The results of this research indicate that the role of Persian letters in the creation of written signs is formed around the meaning and content of the subject; So that the visual form of the letters tells and displays the content of the subject and undergoes a structural and formal transformation in the design process, and these transformations, in addition to the aesthetic search for form, seek to supplement writing and form with meaning and content. . One of the main and distinctive features of Persian script; It is the continuity and connection of letters that creates various forms and shapes. The presence of formal similarities in some letters and their visual composition with multiple placements relative to each other creates creative forms, rhythm and homogenization in the design of written signs.