The behavior of microdischarges and their effects on chemical reaction in a micro-plasma reactor are investigated. A model of the micro-plasma reactor has been constructed to understand the relations of the behavior of microdischarges and chemical reactions. The ozone generation reaction was chosen as a model reaction. The microdischarge properties required for the modeling are acquired by the analyses of microdischarge pictures taken with an ICCD camera, and the electrical characteristics are measured by analyzing Lissajous figures. In the model, we divide the reactor into discharge regions including the effective discharge regions and interval regions, and the non-discharge regions, while considering the appearance and disappearance of microdischarges. To take into account the randomly distributed microdischarges over the reactor, the number of microdischarge columns to meet is also calculated. The properties of microdischarges obtained by experiment are applied to the numerical simulation, and the numerical results agree with experimental ones.