Nest-site selection can have important fitness consequences for birds. Understanding what information individuals use to choose nest sites is therefore crucial not only for understanding the dynamics of populations, but also for the conservation of species. We identified habitat characteristics predicting nest site selection in the threatened Jankowski's Bunting Emberiza jankowskii in Mongolian grasslands. We recorded 14 habitat characteristics around 83 nests of Jankowski's Bunting and at 83 random points at local and landscape scales. Compared with the random points, Jankowski's Bunting nest sites had significantly greater values for plant canopy, grass height and grass density at the local scale, while such significant differences were not found in the percentages of natural grassland or bare cropland at the landscape scale. The generalized linear model performed on selected independent variables confirmed that Jankowski's Bunting nests occurred more often in densely vegetated areas with tall grass and scrubs. This study highlighted the importance of plant cover and vegetation height in the species' nest site selection and suggested that continuous control of grazing pressure is necessary to better conserve the natural grasslands needed for the persistence of Jankowski's Bunting.