The Asiatic wild ass belongs to Equidae and Equus Linnaeus. It is an endangered species according to the International Union for Conservation of Nature (IUCN) and one of the highest class of protected animal species in China. For the purpose of studying the regularity of reproductive behavior, we have observed the Asiatic wild ass’s reproductive behaviors in central Inner Mongolia from February 2004 through November 2016. This is the first study to define and record estrus and mating, parturition and sexual behavior of the Asiatic wild ass in the wild. In the breeding season, there is a difference in terms of the ratios of time for the aforementioned behaviors between mature male and female Asiatic wild asses. The behaviors of a decreasing ratios of time are feeding (40.75%), standing and gazing (23.16%), resting (16.78%), moving (14.72%), sexual behavior (2.55%) and others (2.04%) for mature male Asiatic wild asses and feeding (53.99%), resting (28.35%), moving (6.91%), standing and gazing (6.06%), others (3.02%) and sexual behavior (1.67%) for mature female Asiatic wild asses. It is obvious that the feeding behavior takes the most time for both genders, which can be explained by poor local plants in terms of the amount and the nutrition. In the breeding period, most of members in a population of Asiatic wild asses behave regularly and consistently, with alternating behaviours of resting and activity.