To explore distribution characteristics of TCM syndromes and syndrome essence of primary insomnia through literature research.Methods:Studies on primary insomnia syndrome differentiation from year 2000 to 2013 were collected and analyzed through literature research method and those meeting the enrolled criteria were recorded and checked.SPSS 17.0 software was adopted to analyze frequency and times of syndromes and essence of syndromes.Results:The top three syndromes out of 66 syndromes were deficiency of both the heart and spleen，phlegm-fire harassing the heart and stagnation of the liver qi; the heart，liver and spleen were the top three locations among the syndrome essences; and fire/heat，qi deficiency and yin deficiency were the top three pathogenesis types.Conclusion:At present，distribution of TCM syndrome types of primary insomnia is scattered，while syndrome essence has good covering rate for syndrome differentiation and can unify and standardize clinical syndrome differentiation.