Phylace activity was a theurgy to avoid misfortunes in ancient time. Phylactery has various formats and rich contents. It is an important source material for the study of ancient philosophy, customs and early Daoism. Based on the analysis of a large amount of material, the author discusses several significant questions. Phylace activity was a theurgy to avoid misfortunes in ancient time. Phyctery has various formats and rich contents. It is an important source material for the study of ancient philosophy, customs and early Daoism. Based on the analysis of a large amount of material, the author discusses several significant questions.