Abstract: The new fossils of Bos primigenius in this study came from two regions in Hebei Province: Nihewan Basin (one partial skull with right horn-core and one humerus) and Longhua County (one humerus, one tibia, 2 calcanea and 3 astragali). The humerus from Nihewan has a total length of 457.3 mm, which almost represents the largest aurochs individual which has a two-meter shoulder height. The biggest humerus and other big cranial specimens in northern China can be correlated with the European counterparts of late Middle Pleistocene, and they should be contemporary. The smaller sized limb-bones from Longhua were unearthed from loess deposits, which can be attributed to Late Pleistocene. The current knowledge shows that aurochs may have arrived in China earlier than Late Pleistocene, because its associated taxa, e.g. Canis lupus, Panthera tigris, Mammuthus primigenius,Equus caballus, Coelodonta antiquitatis, Sus scrofa, Camelus knoblochi, Cervus elaphus, Alces alces and Bison priscus have appeared as early as late Middle Pleistocene or even earlier in Eastern Europe and Northern Eurasia. Furthermore, new numerical dating results show that the aurochs’ occurrences from some sites in China can be traced back to Middle Pleistocene. This study proposes that the larger sized aurochs should be of a late Middle Pleistocene age. In China, aurochs fossils mainly occur in the northern part and the transitional zone along the Huaihe River, but are absent in southern China and Southeast Asia, which resulted in the hypothesis of “Central Asian Corridor” through which aurochs reached China. In recent years as more bovini fossils were recovered in Africa, the Bos phylogeny was proposed, which assumed that the evolution of Bos lineage took place in Africa rather than in Eurasia as thought before, and the earliest ancestor of B. primigenius is Pelorovis turkanensis, finally the genus Bos dispersed into Eurasia at the beginning of the Middle Pleistocene. The present authors think that the African Pelorovis species are too different from the Bos lineage in morphology; on the contrary, the early Bosspecies from Siwalik in South Asia resembles B. primigenius very much. In China, most of the B. primigeniusfossils were recovered from fluvio-lacustrine deposits in North China Plain, Loess Plateau and Song-Nen Plain, whereas few of them were from loess deposit, which means that the aurochs fossils could be employed as an indicator of warm climate and wet environment.