Mulla Saalih Mazandarani is one of the famous scholars of 11th century. His commentary on al-Kafi is the best commentary in this field. It is concerned with Usul and Rawza. The author of the present paper describes Mulla Saalih Mazandaranis method based on his commentary on al-Kafi. Then he explains about Allama Sharanis methodological criticism of some views of Mulla Saalih Mazandarani. His method of evaluating hadith is based on investigating the chain of documents and interpreting the text. His approach to text analysis is based on terminology, semantics, verses of the Holy Quran, and utilizing other hadiths to prove hadith reliability.