The Shimen As(Au) deposit in Hunan Province, characterized by a pipe-shaped orebody and typical structural model of three layers, is belived to be of hot spring origin. Systematically described in this paper are such genetic mineralogical features of realgar from this As(Au) deposit as its mode of occurrence, chemical composition, physical properties, unit-cell parameters, infrared spectra and sulfur isotopic composition. The realgar is high in S but low in As,and contains Sb and trace amounts ofHg, Se, Te, Bi and Au. Unit cell parametersa0=9.309 ~9.511°A,b0=13.52~13.61°A,c0=6.572~6.593°A; crystallochemical formula (As0.9997 Sb0.0013)1.0010S. Infrared absorption appears at 343 and 375 cm-1;δCe<1, exhibiting obvious negative anomaly. These typomorphic characteristics are of great significance in the study, evaluation and prospecting of other realgar deposits (occurrences).