The theory and the application of natural ventilation were reviewed. Wind-induced pressure and thermal pressure, are two basic factors contributing to pressure-driving mechanism of wind flow. Wind-induced pressure, which is resulted from the difference of air pressure when wind flow is blocked, is significantly influenced by the shape of building, and it may cause Bernoulli effect and the ventruri effect. Thermal pressure depends on the temperature difference between incoming and exhaust air. Because of thermal pressure, stack effect comes into being when air in the building warms, becomes more buoyant than outside air and rises to escape out of openings. Commonly, the natural ventilation we often refer to is the combined effect of wind-induced pressure and thermal pressure. Several typical cases of the application of natural ventilation are introduced in the paper and some possible problems about natural ventilation are described.