Abstract: The paper studied the mammalian fossils found in loess layers of north China, and conducted the comparison between biostratigraphy and magnetosfratigraphy. The mammalian faunas in Chinese loess were divided as following: Early Pleistocene (2.50 —0.73 Ma): Wucheng nummalian fauna (2.50 — 1.20 Ma), Gongwangling mammalian fauna (1.20 — 1.10 Ma), Yangguo mammalian fauna (1.10 —0.90 Ma); Middle Pleistocene (0.73 —0.13 Ma): Chenjiawo mammalian fauna (0.73 —0.40 Ma); Late Pleistocene (0.13 —0.01 Ma): Rouyuan—Jingyuan mammalian fauna (0.13 —0.01 Ma); Recent (0.01 Ma — Rec): Banpo mammalian fauna. The result shows: In Early Pleistocene there were many fossils of forest animals in the loess layers, which reflect that the climate in the Early Pleistocene was cooler than that in the Pliocene, but warmer than that of the later stages. Because the climate in the Middle Pleistocene was cooler and drier than that in the late stage, the forest was narrowed down or disappeared gradually. Correspondingly, grassland and drier steppe were getting expanded. Most of the mammals appeared in the strata were the dwellers of grassland and drier steppe. In the late Pleistocene, the climate was far cooler and drier, which made even parts of the areas become sandreld. The fossil of Meriones sp. and Struthilithus sp. were found in the loess layers of this period.