The present invention relates to the pentasaccharide in acid form and its pharmaceutically acceptable salt as shown in formula (I), and its anion form, wherein R 1 is (C 1 -C 3 ) alkyl; R is hydrogen, -SO 3 - , (C 1 -C 3 )alkyl or (C 2 -C 3 )acyl; T is hydrogen or ethyl; and n is 1 or 2.