The species of the subfamily Sciurinae are widely distributed in China, which play an important role in the dispersal of plant seeds and are considered an important animal group to maintain the ecological balance in forest ecosystems. From November 2016 to November 2017, we used line transect and camera-trapping methods to survey the Sciurinae species in Mentougou District, Beijing. Thirty-three line transects and 72 camera-trapping stations were established in total. The length of all line transects was 205 km and the total camera-trapping efforts accumulated to 5 059 camera-days. Four Sciurinae species were identified, among which Sciurus vulgaris is a new record for Mentougou District, Beijing, and Sciurotamias davidianus is a species endemic to China. S. davidianus has the highest relative abundance, followed by Sciurus vulgaris and Tamias sibiricus, and Tamiops swinhoei the lowest. The four squirrel species occur sympatrically in some areas, and competition among species is likely reduced due to the difference in their activity time. This research elucidated the distribution and abundance of Sciurinae species in Mentougou District of Beijing, providing basic information for their subsequent monitoring and protection management.