The Carbon Bond Mechanism Ⅳ has been developed for use in urban- and regional-scale oxidant models. The photochemical mechanism, CBM4, contains extensive improvements to earlier carbon bond mechanisms in the chemical representations of aromatics, biogenic hydrocarbons, peroxyacetyl nitartes, and formaldehyde. Ozone is produced mainly by nitrogen oxides and hydrocarbon. By altering the initial concentrations of the mechanism, an analysis of the sensitivity of ozone concentrations to VOC/NOx ratios and VOC composition is conducted in this one-dimensional mechanism. Note that it is considered a chemical mechanism in order to understand the photochemical reactions within this mechanism. It analyzed the results of these simulations by applying a NOx-sensitive and a VOC-sensitive regime. These sensitivity regimes are changed to match the relative contribution of VOC and NOx concentrations to ozone production in simulations of two sets.