Objective To study the mandibular characteristics of the modern population in Beijing region. Methods  In this study, we examined 22 measurements and their sexual dimorphism index (SDI) of 193 adult mandibles (126 males, 67 females) collected from the Beijing region. In addition, eight mandibular indexes were calculated. These mandibular dimensions of the Beijing population were compared with those of other modern and contemporary populations in Asia, as well as Neolithic-historical populations in Northern China. Results  The predominant mandibular index in the contemporary Beijing population was dolichostenomandibular. The SDI of mandibular size exhibited a wide range of variation. It was noteworthy the minimum height of mandibular ramus, height of mandibular ramus, height of coronoid process and minimum breadth of mandibular ramus demonstrate significant sexual dimorphism (SDI ≥10%). The mandibular size aligned with the variation range of modern and contemporary Asian populations, with the cluster analysis indicating an affiliation with Northern Mongoloids. But the Beijing population was far away from other Northern populations in China. The mandibular size was more gracile compared to ancient populations in Northern China, whereas the height of mandibular ramus was greater than those of the latter. Conclusion  This study provides valuable insights into the physical characteristics of modern populations in Beijing region.