The present study aims to identify the factors effective in the grading of university students' examination papers from the perspective of instructors, employing an interpretivist nature and a qualitative approach of a phenomenological type. The participants of the study included all faculty members of Iranian universities during the academic year 1404-1403, from whom 19 instructors were selected through purposeful sampling of a desirable type, considering theoretical saturation. The data collection tool was a semi-structured interview, and after determining the research objectives, the data were recorded and transcribed. The thematic analysis method was used for data analysis. The findings revealed that the most important factors affecting the grading of examination papers included factors related to the instructor, factors related to the student, the presented curriculum, the university environment, university rules and regulations, and the examinations themselves. Ultimately, it can be said that by identifying the influential factors on the grading of examination papers and providing effective solutions, a significant portion of the challenges related to the grading process can be addressed.