Mulla Mohammad Saleh Mazandarani is one of the prominent thinkers of the 11th century. The only work that reflects his opinions and theological opinions is the book "Sharh al-Kafi". In this work, he has described and explained theological topics in accordance with the narrations that contain theological topics. According to the type of theological problem, Mazandarani has used various intellectual and narrative sciences. In order to prove or explain the concepts and issues of belief mentioned in the narrations of the Kafi book, he has used a lot of Quranic verses and other narrations, but his approach to those theological issues in which it is permissible to use reason and narration is rational and in Their proof or explanation has benefited from intellectual thinking with a philosophical color. Expressing the views and opinions of thinkers of different sects and religions in many theological topics is one of the other characteristics of his theological method.