Introduction
 Semiotics is a science that deals with the understanding and analysis of signs and symbols in all forms and aspects. The external forms of buildings have always shown the unique styles of each period through the appropriate use of social, cultural and technological backgrounds. An exterior form expresses important issues such as: material properties, form-making techniques, and productivity. With the beginning of the second Pahlavi period, Iranian architecture entered a new phase. During the time of Pahlavi II, the model of modernism was widely reflected in the development of the country's cities, and the construction industry in Iran took on a modern appearance. Therefore, until that day, the influence of western architecture on Iranian architecture was limited to imitating some elements and combining different styles of European architecture with native methods of Iran. The current research seeks to know the relationship between the art of creating architectural form and the factors that create signs. In fact, this recognition and examination occurs in the context of architecture, because meaning and sign are a part of architectural form. Although in the past architecture of Iran, the part and the whole were in harmony and were created simultaneously, but the expansion of science and technology and the ever-increasing need for construction caused a divergence between these components and sometimes the architectural form went out of balance and towards staging. Mere or purely guided symbolism, the need to reunify these factors and components, this time on a wider scale. Therefore, in this research, relying on the theories of semiotics, while knowing more about the evolution of the architectural form in some significant works of the second Pahlavi period, we will try to identify and analyze the meanings and signs that can be interpreted in the architectural form of this period. The main question of the research is, what are the elements of the architectural semiotic system of Pahlavi II period and how do these elements affect the architectural identity of this period? The following assumptions have been made from the question: It seems that the contrast between tradition and modernity has had the greatest impact on the semiotic evolution of the architecture of the second Pahlavi period in Iran. It seems that the semiotic evolution of the second Pahlavi period architecture throughout Iran was influenced by the intellectual developments of the world. Research
 
Methodology
 In this research, in order to check the validity of the scale and content of the measurement tool (questionnaire questions) with the research variables, the face validity method was used. In the current research, referring to the qualitative method and using the interview technique, the opinion of professors and experts in the field was asked about the designed questionnaire. Finally, by applying the comments, the measuring tool of the research variables has been approved. In this research, in order to ensure the reliability of the research, two methods of Cronbach's alpha and the coefficient of inconsistency have been used to use the AHP technique. In this way, Cronbach's alpha has been measured for all research components and its value was 0.749, and therefore, because it is higher than 0.5, the overall alpha has been approved at the desired level, and then in order to ensure Pairwise comparisons and reliability of data in each of the components of the research, the inconsistency coefficient has been calculated using super decision software.
 
Results and Discussion
In this research, each of the selected buildings from the most important buildings of the second Pahlavi period in Iran, i.e. the buildings; 1. Bu Ali Sina Mausoleum, 2. Senate-Islamic Council Building, 3. Nader Mausoleum, 4. Kamal al-Molk Mausoleum, 5. Azerbaijan Museum, 6. Khayyam Mausoleum, 7. Shafaq Park and Cultural Center, former Yusuf Abad, 8. Central Building Sepeh Bank, Topkhaneh Square, 9. Nain Guest House, 10. Shahyad Aryamehr Tower (now Azadi), 11. Shahr Theater, 12. Harvard University Management Studies Center (now Imam Sadeq University), 13. Azadi Stadium, 14. Sharif University of Technology, 15. Contemporary Art Museum, 16. Al-Shaara Tomb Memorial, 17. Carpet Museum, 18. Niavaran Cultural Center, 19. Shiraz University and 20. Faculty of Business Administration, University of Tehran from the dimensions of form, materials, decorations, geometry and color using We have investigated the hierarchical analysis technique to determine the position of each building in the semiotic structure. Considering that in the hierarchical structure of semiotics, the symbol is at the highest level and the icon is at the lowest level, if we categorize them in a ranking spectrum, the highest score will be 4 for the symbol and the lowest score for the icon will be 1, so the average If it is close to 4, it means that component in the semiotic structure tends to the symbol level, and if it is closer to 1, it means that it is on the icon level. Between these two levels, there are two levels of profile-image with a score of 2 and profile with a score of 3, where the average of the components shows the position of each component in this structure. Based on the pairwise comparison, taking into account the geometric mean and special vector, the normal and ideal weight of each component is calculated and the results show that the form component has the highest weight and the decoration component has the lowest weight.
 
Conclusion
By examining the researches and studies carried out in the semiotic field of contemporary Iranian architecture, it seems that understanding the architecture of the second Pahlavi period and the architectural identity of this period along with the changes and transformations that occurred in the heart of architecture in the transition from tradition to modernity and with the involvement of all factors Foreign in it has been the attention of architects and researchers. But the distinguishing feature of the current research is the attention to the semiotic nature of the works of the second Pahlavi period in the form of quality assessment of the studies conducted in recent years. Undoubtedly, identifying the factors affecting the changes and developments that occurred in the semiotic structure of contemporary architecture in Iran and explaining and investigating these causes and factors will greatly contribute to the identity of contemporary Iranian architecture, which needs to be paid more attention to researchers in future researches.