This paper studies the association between concentration of ambient air pollutants and daily mortality number in an urban area of Beijing. Different age and gender groups were taken into consideration. The results showed that, for all the groups, the average daily mortality number showed an increasing trend from June to January of next year, and a decreasing trend from February to June. When the concentration of air pollutants increased, the health risk also increased. In multi-pollutants models, the pollutants had a decreasing order NO₂, PM₁₀, SO₂ for the different gender groups when the concentration of pollutants increased, and had a decreasing order NO₂, PM₁₀, SO₂ for different age groups when the levels of pollutants increased. Lag effects of air pollutants and seasonal differences also were found. The results of our study could serve to strengthen the local evidence base for air pollution-related health effects that is imminently needed for better air quality management, and also adds valuable information from Beijing.