Disclosed are 4,5-diamino-3-halo-2-hydroxybenzoic acid derivatives and manufactures thereof. The 4,5-diamino-3-halo-2-hydroxybenzoic acid derivatives are presented by formula (I):wherein R1 group is H, CH3, or C2H5 R2 group is H, or Br R3 group is CH3, or C3H7 and R4 group is H, or C(═NH)—NH2. 4,5-diamino-3-halo-2-hydroxybenzoic acid derivatives provided here were non-toxic to MDCK cells, particularly compounds 6a, 6b, 6c, 6e, 6f, 7a, 7b and 8 had better anti-H1N1 activity. In the future, these compounds can be used to focus on viral neuraminidases as targets to develop effective anti-influenza drugs.
