Abstract：This paper introduces the clinical experience of staged treatment of infectious mononucleosis (IM) based on the theory of truncation and reversal. The authors believe that IM can be divided into three stages of treatment， namely the early stage， the extreme stage， and the late stage. The theory of truncation and reversal is beneficial for the quick control of the condition of disease， blocking its progression， and reducing the occurrence of severe symptoms. At the same time， clinical medication should pay attention to the care of children's stomach qi to avoid causing damage to their healthy qi.