In archeological studies of the historical period of Iran, the Sassanid period is considered as a period in which the role of religion is more prominent than any other socio-cultural case. Sassanid ChaharTaqis are also known as the most important symbols of religious architecture of this period. Although these structures look similar to each other in general, they have significant differences in details. One of the most important ambiguities related to the Sassanid religious ChaharTaqis is their religious function and quality. In this research, an attempt has been made to study a type of Sassanid ChaharTaqis that has only a surrounding corridor and does not have any other architectural extensions. This research is trying to determine their function and religious quality. For this purpose, two ChaharTaqis of QotbAbad and Mazayejan, located in the eastern regions of Fars have been considered. The purpose of the study is to review the plan of both buildings and provide a better understanding of their religious function. In this article, an attempt has been made to answer the question of what the rank of the mentioned religious quality is. The hypothesis that can be put forward for this question is that the ChaharTaqis seem to be probably related to the court fire and have the lowest religious rank. This research is a kind of fundamental research and from the perspective of the nature and method of research is a historical and descriptive-analytical study. The method of data collection is field library and laboratory. The results of this study indicate that ChaharTaqis which has surrounding corridors and does not have any other architectural extensions can be used as Yazišngah. They are related to the fire of the court. The significance of this research is that it reviews the plan of buildings and it also offers a new function for a group of religious buildings of the Sassanid period.