Fine particles are complex mixture of air pollutants containing not only a great deal of organic compounds but also varied kind of metals, such as B(a)p, Pb, Cd, Cr etc. Most of those compounds are toxic. Some of them are the cause of lung inflammation and asthma, some are genotoxic with a potential of carcinogenesis. Because the fine particles can be inhaled into lung and deposit in lung tissue, which have adverse effects on human health. Epidemiological studies indicated that increased mortality and morbidity, especially for cardiovascular and lung diseases, was associated with the amount of ambient fine particles. Although some scientists thought fine particles damaging the body through oxidant stress, inflammation and genetic materials and so on, the mechanism for them is not known well. Therefore, it is necessary to explore the biological effects of fine particle on human health in the future.