The infrared absorption spectra of different superconducting phase of high Tc super conductor Bi-Sb-Sr-Ca-Cu-O have been measured . The results show that only in the range of 400cm-1 -700cm-1,there is a group of peaks which changes with different superconducting phases.According to group theory and infrared spectra of CuO, this group of peaks could be assigned to be the [CuO6]octahedron, the [CuO5] pyramid and the [CuO4]plane quadrilateral,but not CU-O plane or CU-O chain. Furthermore, the quasi-three dimensional Cu-O layers consisting of [CuO5] pyramids and proper coupling between them are essential factor for high Tc. It seems that the weaker compling of layers, the higher Tc
