The dynamic changes of the oxygen and carbon dioxide volume fraction of Agaricus bisporus which were packaged in three kinds of film with different thickness were studied at 2℃ and 20℃. The results indicated that low temperature and MAP could inhibit the respiration of mushroom. A respiration model, based on Michaelis-Menten type enzyme kinetics, was proposed for predicting respiration rates of Agaricus bisporus as a function of O2 and CO2 volume fraction at the storage temperature of 2℃ and 20℃, which is essential to the design of modified atmosphere package.