Iranian Naskh script, as one of the most important scripts for writing the Quran, reached a stage of visual maturity in the Qajar period with the continuation of previous traditions and the emergence of new stylistic features. One of the basic elements in the structure of this script is “Kursibandi” which plays a decisive role in the readability, order of lines and aesthetic quality of the text. The present study, with a descriptive-analytical and comparative approach, examines the structure of kursibandi in Iranian Naskh script in the works of two prominent calligraphers of the Qajar period, Zain al-Abedin Isfahani (Ashraf al-Kottab) and Vesal Shirazi, focusing on the writing of Surah Yasin. The aim is to compare the position of letters on the kursi script, the spaces between the khalut and jalut, the arabes and dots, and the arrangement of lines in the script of these two artists. Therefore, the main question of the research can be stated as follows: What are the similarities and differences in the kursi structure of the Iranian Naskh script in the Ashraf al-Kitab and Wisal Shirazi scripts? The research data was collected through the study of selected manuscripts, visual analysis of lines and examination of the position of letters on different kursi. In this study, elements such as the main kursi, upper and lower kursi, line slope, spacing, letter juxtaposition and word arrangement were compared. The findings show that both calligraphers have succeeded in observing the fundamental principles of kursibandi, with the difference that Ashraf al-Kottab has created a better kursi balance in some verses due to the selection of shorter lines and more precise control of the spacing, while Vesal Shirazi has maintained the readability and overall order of the page with longer lines and a uniform layout. The results of this study can help to more accurately identify the characteristics of kursibandi in Iranian Naskh calligraphy of the Qajar period and to understand individual differences in the writing style of calligraphers.