The recent progress on studies of the Quaternary glacial-interglacial epoch which relates to the Milankovitch astronomical theory of paleoclimate is presented. The different large glacial-interglacial changes with cycles of  100－120, ≈40 and 20 thousands years are found in the data of global  ice volume, which is implied by the data of oxygen isotope ratio in the deep sea. The similar period terms above in glacial-interglacial climate changes are also documented by complementary climate records derived from different data of geology, such as the deep sea sediments, the records of polar ice core's δ¹⁸O from Vostok and the central Greenland, the magnetic susceptibility data of loess profile in China and so on. According to the Milankovitch astronomical theory of paleoclimate, the variations in the geometry of the Earth's orbital elements are the fundamental source of the succession of Quaternary ice age. Hence, it is the global effects that caused by the climatic variations. Milankovitch astronomical theory of paleoclimate is basically reliable. However, the deficiency in this theory and the possible external mechanism of the glacial-interglacial changes with cycles of  100－120 thousands years are introduced and discussed.