Minimal important difference (MID) is a concept in regards of efficacy evaluation in recent years. MID has its features and clinical significance. MID methods include anchor-based methods, distribution-based methods, expert consensus methods, literature analysis methods, and so on. All these methods have their own advantages and disadvantages. In confirming MID, you'd better use them comprehensively according to the research objectives. The significance, range, and evaluation methods of MID in the clinical research of Chinese medicine were clarified. It is necessary to strengthen MID correlated researches and applications.