Primary burning mouth syndrome（BMS）is defined as a chronic intractable mucosal painful disease characterized with tongue as the main lesion and ongoing（chronic）or recurrent burning in the mouth as the main symptoms，but without significant clinical damage，histological changes and obvious causes. Due to its unclear epidemiology，etiology and pathogenesis，there is lack of standardized diagnostic criteria and effective treatment. The present study reviews five aspects of BMS，including the evolution of BMS terminology and classifi⁃ cation，pathophysiological mechanisms，diagnostic methods（questionnaires，imaging examinations，and serum or saliva tests），and therapeutic diagnosis. In the future，with the in⁃depth clinical practice and research，BMS patients may benefit from a deeper understanding of the pathological mechanism and the proper use of diagnostic tests.