Active aging is the scientific policy framework to deal with the population aging.The seniors' social participation has an important meaning for active aging construction.The paper, using the perspective of functionalism, takes the example of Z community in Beijing, and analyzes the social participation of the elderly people from the political, economic, cultural, and community aspects.The study reckons that the low level social participation of elderly people is influenced by individual and social factors.The development of the elderly social participation needs the dual efforts of the society and the seniors themselves.