The Tianyuan Cave is the only human fossil-bearing site containing rich mammalian fossils found in the last decades near Zhoukoudian. Up to now more than 34 specimens of the human body have been recovered, and the mammalian fossils can be put into 29 species. Cervids dominate the fauna, and carnivores are very rare. Based on the primary examination, the human fossils can be attributed to the species Homo sapiens. All the mammalian fossils, except one between tooth of Crocuta belong to the species that still exist today. But some of them are the first records in fossil form north of the Yellow River, such as Arctonyx and Capricornis. Based on the mammalian fauna study, it seems that the Tianyuan Cave can be correlated with the Upper Cave. Sixty-three percent of the species of the mammalian fauna from the Tianyuan Cave are also present in the Upper Cave. The characters of the deposits also share some similarities between the Tianyuan Cave and the Upper Cave; both of them are mainly composed of breccia without cement. The dating using the U-series method on deer tooth samples indicates that the geological age of the new site is around 25 thousand years B.P. This is the first discovery of human sites outside the core area of the Peking Man Site at Zhoukoudian, which throws new light onto this world famous site complex.