There has always been a taxonomic controversy over the Middle Pleistocene raccoon-dogs, such as those from ZKD (=Zhoukoudian), which have previously been referred to either as Nyctereutes sinensis or N. procyonoides. Here, the specimens from ZKD Loc.1 and 13 have been re-evaluated and a number of diagnostic features have been identified and summarised. It is strongly recommended that they be classified as a new species, Nyctereutes peii, characterised by the robust dentition. The rationale and necessity for the establishment of N. peii has also been addressed from a number of perspectives. In addition, the evolution of the raccoon-dog’s foraging habits was outlined here for the first time using the molar ratio method. Surprisingly, the evolution of the foraging habits is not linear and gradual, but rather complex or tortuous. N. peii unexpectedly showed a less omnivorous habit than other populations. After that, however, there was a sudden reversal in the evolutionary trajectory, a major turning point in the evolution of the raccoon-dog that heralded the arrival of the extant population. Although the mechanism and dynamics are not fully understood and will need to be studied, the authors suggest that it may be linked to the dramatic fluctuations in global climate.