We have measured Raman spectra of HgBa2Ca2Cu3O8+d (Hg-1223) superconductors. The spectra show peaks at 92, 127, 138, 230, 479, 538, 574, and 585 cm-1. From a factor group analysis and the structural information about Hg-1223, we assign the modes at 92, 574, and 585 cm-1 to be A1g modes of Ba, O(2) and O(3) atoms, respectively. The modes at 479 and 538 cm-1 are proposed to be Eg modes of O(3) bending and O(2) stretching vibrations, respectively. Details of mode assignments are given in the discussion.