Placenta ingestion is a crucial event in mammalian parturition which provides insight into understanding for both ecological and biological functions of reproduction. However, parturition in wild mammals mostly occurs at night, placing restrictions on observationand is seldom observed by researchers. Thus, little has been known for parturition in wild animals, especially for wild nonhuman primates. We occasionally observed a primiparous adult female Tibetan macaques (Macaca thibetana) named THY ingesting placenta during the postpartum phase at 8:59 AM of April 9, 2015. Immediately, we used a focal sampling method and continuously recorded THY' s behavior during placenta ingestion. The whole process included licking, tearing to pieces, scraping and swallowing, and lasted for two hours and 29 minutes. The effective duration of THY' s placenta ingestion is more than 63 minutes. Therefore, placenta ingesting in primiparous Tibetan macaques took longer than it does in other nonhuman primates. Moreover, during placenta ingestion, the female participated in more social interactions with others compared with other species. We also found that the female showed vigilant behavior during the process of placenta ingestion. Our study provides the first evidence on parturition in Tibetan macaques and offers a new insight into understanding the parturition traits of the species.