Population aging is an important population situation in the process of modernization construction in Beijing. This paper uses the data of the China Seventh Census to describe and analyze the size，structure，and economic and social features of the elderly population in Beijing. The study found that the size of the permanent elderly population aged 60 and above in Beijing has grown rapidly，currently the number of this group of people has reached more than four point four million，including one sixth of the migrant elderly population. The proportion of the young elderly population has increased significantly，reflecting the rapid aging characteristics of the past decade. The education level of the elderly is concentrated in junior middle school and below，but the proportion above junior college has increased significantly，providing a good foundation for the development of human resources for the elderly. The proportion of old people who live alone accounts for 10%，and widowed elderly people takes up around 10%，People in need of family and social support account for one tenth，and unhealthy elderly people account for nearly five hundred thousand. The government should attach great importance to the above situations and build up a basic social assistance system.