To understand the behavior patterns, including the time budget of endangered animals is important to make better conservation measures. During March to October in 2016 and 2017, we observed the behaviors of 4 pairs of Cinereous Vulture (Aegypius monachus) and their nestlings during the nestling period, using the focal sampling method and all occurrence recording method, in Hejing County, Xinjiang, China. The study area is located in the Tianshan Mts (42°50′﹣43°02′N, 86°03′﹣86°32′E). Two or three infrared cameras were set up around each nest and about 110 thousand photos with over 90 h videos were captured. We also observed the behavior of parents and nestlings, 400﹣600 m far away from the nest, for 35 d (412 h) during the nestling period. All the behaviors of Cinereous Vulture, defined by the postures and actions, were classified into 9 categories (including 33 behaviors) for parents and 6 categories (including 28 behaviors) for nestlings according to the motivations and functions. During the nestling period, caring, alerting and looking of the time budget of parents and resting and looking of nestlings were dominant. The times of feeding the nestlings from the parents reached the peak at 12:30﹣13:30, followed by the second peak at 15:30﹣18:30 (Fig. 2). The length of nestling period of Cinereous Vulture lasted for (97 ± 6.16) d (90﹣105 d), and we divided the entire nestling period into three stages (Pre-nestling: April and May, Mid-nestling: June, Post-nestling: July) and analyzed the time budget of parents and nestlings during the three stages (Table 1 and 2). The time budget of pre-nestling period was analyzed according to the videos, and the other two stages were analyzed according to the observation supplemented with the data of cameras by time. The differences of these budgets were tested by one-way ANOVA. We found that: there was no significant difference between the time budget of pre-nestling and post-nestling of parents (P > 0.05) while either the difference between pre-nestling and mid-nestling or between mid-nestling and post-nestling was significant (P < 0.01); the difference between any two stages of nestlings was significant (P < 0.01). During the post-nestling period, the defecating numbers of nestling (3.52 ± 1.92) was much more than the feeding numbers from parents (0.93 ± 0.96) which, we believed, was related to the behavior of food storage and bad weather (Fig. 3). As the nestling period progressed, the time of first return of parents with food was gradually delayed (Fig. 4), we suggested that lack of food and anthropogenic factors might influence the breed success of the Cinereous Vulture in Xinjiang.