A theoretical and experimental study of intersubband absorption in p-type GexSi1-x/Si multiple quantum wells are presented,the calculations are performed with envelop-function approach,with full inclusion of the degeneracy and warping of the three topmost bulk valence bands described by the strain-dependent Luttinger-Kohn Hamiltonian.The Hartree potential and the exchange correlation interaction are taken into account in a self-consistent manner.And finally the absorption spectra is calculated.We contribute some absoptions observed with normal incident unpolarized infra-beam to the band-mixing of heavy,light and split-off bands in GexSi1-x/Si quantum wells.