Thematic exegesis at the beginning of the chapters of Bihar al-Anwar is a matter that researchers and authors have commented on it and they know him as the beginner of thematic exegesis. He briefly used this method of exegesis (Sobhani, 1981: Vol.1, p.2). Research on the validity of this view can be performed in three parts of gathering chapters, sub-chapters, examining the viewpoints of exegetes and analysis and conclusion according to the definition of thematic exegesis. This study aimed to study the thematic approach of Majlesi to the Quran which is the introduction and entrance basis to thematic exegesis. For this purpose, the number of chapters were randomly and proportionally selected from each subject package of Bihar al-Anwar and then examined. Totally, proportion included about 100 chapters with their titles. According to the results, on the one hand, coverage and diversity of the subjects of Bihar al-Anwar are proved and on the other hand, it is proved that each chapter includes all related verses. Also, the order and coherence of Majlesi’s method at the entrance to the exegesis of verses becomes clear.