Based on the observation data of ozone and its precursor compounds and meteorological factors in near surface layer of Chongqing urban area，this paper emphatically analyzes the temporal and spatial distribution characteristics of ozone in summer. Meanwhile，the correlation between ozone and its precursor compounds，such as NO，NO2，CO，and some related meteorological factors are analyzed. Results show that the concentration of ozone in urban area is lower than that in the surrounding regions. Only one peak of ozone concentration appeared in about 4 p.m. The ozone concentration has an obvious negative correlation with precursor compounds，and has obvious positive correlation with meteorological factors，such as solar radiation and temperature. The appearance of high ozone concentrations resulted from the high pressure weather conditions，especially for the high intensity of solar radiation，breeze，low relative humidity and high temperature. Elevated ozone concentration is closely related to the decrease amplitude of atmospheric pressure. Higher ozone concentrations appear when the decrease amplitude is 0.4 kPa.