[Objectives] The Great Bustard (Otis tarda) is a Class I protected species in China. Analyzing the population trends of the Great Bustard in important habitats will provide a scientific basis for protection and management of the species and its habitat. [Methods] From 2017 to 2020, a total of 33 monitoring sites were selected (Fig. 1) and comprehensive surveys were conducted on spatial and temporal changes in the population and distribution of Great Bustards in the Tumuji National Nature Reserve (eastern Inner Mongolia) and nearby areas. The number, sex and distribution sites of the Great bustard were investigated. [Results] The population of Great Bustard in our area increased from 193 ind in 2017 to 253 ind in 2020. The monthly number of birds varied, with the peaks in May (> 200 ind) and October (> 100 ind) and fewer in December to February of the following year. The winter population was approximately 50﹣70 individuals (Fig. 2). The winter population in January declined from 67 ind in 2017 to 55 ind in 2019 but recovered to 67 ind in 2020. Females were recorded from March of each year, with the peaks in April and May reaching to 50﹣70 individuals; their numbers declined in June but increased again slightly in September. No females were observed in the wild after October. In April, when Great Bustards were easy to observe in the field, the average female-to-male ratio was 1︰2 (Fig. 3). In 2017 and 2018, the population was stable and widely distributed in the Maanshan area of southeastern Tumiji Nature Reserve, but the number of distribution sites decreased in 2019 (Fig. 4), which may be related to the increase of human disturbances. The functional areas of the nature reserve were adjusted in 2020, and the Maanshan area, which had been removed in 2014, was again zoned as part of the protected area; this increased the area of wetlands and grasslands (Table 1), and the number of Great Bustard distribution sites was gradually restored. [Conclusions] The surveys indicated that the population and distribution of Great Bustards are greatly affected by human disturbances. In order to manage the ongoing problems in Tummuji National Nature Reserve and strengthen the protection of the Great Bustard populations and their habitat, some protective measures are needed, such as restoring farmland to grasslands, strengthening the management of conservation gaps and banning grazing.