Mineral compositions of x1 core sediment samples from Beibu Gulf were studied by the X-ray diffraction method. The parameters Mc/Q, TF/Q and P/K revealed the sedimentary environment changes from Pliocene to Holocene, and showed that the studied area was shallow sea facies environment during Pliocene and Holocene, and that the land facies sediments were mainly distributed during Pleistocene, but that the transgression sequence was formed in the middle stage of Late Pleistocene.