Abstract:Based on a systematic search for the herbal nature of Sargassum in classical traditional Chinese medicine (TCM) books < Shennong's Classic of Materia Medica >, < Appendant Records of Famous Physicians > and < Extrinsic Materia Medica >, the compatibility of Sargassum was concluded in books < Surgery Authority >, < Standards for Diagnosis and Treatment > and < Golden Mirror of Medicine > and the medication feature, compatibility law, clinical application regularity of Sargassum was summarized. The results showed that S. pallidum and S.fusiforme had been listed as ‘Haizao’ since the 1963 version of Chinese Pharmacopoeia. However, other seaweeds, most of which belong to the Sargassum genus, were used as ‘Haizao’ in different regions in China. It was often a difficult task to identify these Sargassum species. The processing methods were different in classical TCM books. Sargassum was washed quickly and cut into sections according to the modern processing method. The medicinal characteristics of Sargassum were bitter, salty and cold, which were similar in classical TCM books. Sargassum was used to treat goiter, scrofula, swelling and pain of testes, oedema due to retention of phlegm and morbid fluids. < Discussion on Property of Materia Medica > stated that Sargassum was little toxic, which was different from other ancient Chinese medicinal books. Sargassum was used to treat various diseases such as goiter, scrofula, edema, beriberi and difficult urination clinically. The contraindications of Sargassum indicated that it should not be used excessively. The pregnant women should avoid using it. People who were weak, deficiency in spleen and stomach should use it carefully. In addition, Sargassum and Glycyrrhizae Radix et Rhizoma were incompatible herbs based on TCM documents. The review of the resource, processing, clinical application and contraindications of Sargassum is the foundation for the modern research. The results would have guiding significance for the clinical application, pharmacodynamic and pharmacological study of Sargassum.