Nowadays, with the development of cities and urbanization, the need for security in various areas is felt more than ever, yet, it is different from what it was before. Meanwhile, psychological security is considered as one of the main and decisive parts of the security concept in urban spaces which is greatly affected by different variables. One of these variables, the effect of which on the sense of security in a place is the subject of this article, is physical visibility in urban environment. This study aimed to investigate the relationship between the visibility of the body of urban squares - as a type of urban space - and the psychological security of the said spaces in the mind of pedestrians. In this context, a review and evaluation will be discussed in Saat and Namaz Squares of Tabriz. In order to evaluate and analyze visual data based on the natural movement of the observer in the urban space, Isovist 3D technique, and Geoweb3D software were used. Moreover, digital interactive modeling (simulated by Unity 3D software) was used to assess the impact of physical changes on visibility and in turn, the psychological security of the environments under study. In this study, from among the various components affecting psychological security in urban spaces, four components, i.e. space, form of space, visual comfort and permeability, were investigated as the most important physical factors affecting the psychological security. The results of assessments carried out showed that spaces with better indices of visibility (such as the volume of visibility, the layout of forms defining the volumetric structure of space, location and dominance of remarkable anchor points visible in space, etc.) are much more effective in altering the perception of the environment compared to other physical aspects, and contribute to a sense of psychological security. This research is a descriptive-analytic and applied research and field, library and documentary methods (with interviews and questionnaires) were used for data collections. Also, visual data analysis modeling has been utilized. The results of data analyses show that Saat Square of Tabriz, with limited sight range and more spatially defined familiarity, is more successful compared to Namaz square in providing a better and safer place in the minds of citizens.