With one-dimension photochemical model,the simulation is conducted on the diurnal variation of O_3,NO,NO_2,CO and SO_2 on 9 September 2001 in stable weather and the controlling factors for the diurnal change are explained.The preliminary analysis shows that the O_3 concentration is sensitive to non-methane hydrocarbon(NMHC).The increase or decrease of NMHC concentration results in the distinct variation of ozone concentration.The cause of NO,CO and SO_2 concentration increase from 20:00 to 23:00 on 9 September 2001 is the weak vertical diffusion and accumulated pollutants at the lower atmosphere at night.The producing and depleting mechanisms of O_3 are complex and the transportation is important for O_3 and its precursors.Though one-dimension model can reveal the main factors influencing O_3 concentration,the three-dimension model is needed to explain more phenomena.These conclusions are derived only from a few experiments.The O_3 pollution in summer over Beijing is very complex,needing further study and validation.