Based on the observational data of near surface O3, NO, NO2, CO and meteorological factors in the urban area of Ji'nan during summer 2003, the 03 concentrations and their temporal variation characteristics were studied. The correlation between O3 and its precursors (NO, NO2, CO) and related meteorological factors (solar radiation, temperature) was analyzed. The results show that O3 pollution during summer was very serious in Ji'nan, and the levels of O3, NO, NO2, NOx and CO were quite high during the observational period. O3 concentrations were well negatively correlated with NO, NO2, NO, and CO during day time. As to the meteorological factors, O3 concentrations correlated well with solar radiations, but showed no obvious correlation with the temperatures. Consequently, based on the above data and results, a regression equation that relates ozone concentrations observed in the day time to its precursors and solar radiation was constructed. The results show that the calculated values were in good agreement with the observed values.