Abstract: Oxidation of ethylene to acetic acid is a new technology developed recently. Study on this new technology has great influence on the ethylene acetic aldehyde acetic acid technology used in China. This paper analyzed the mass balance of ethylene oxidation to acetic acid. The expressions of converstion and selectivity were got. The analysis of reaction equilibrium and heat effect shows that it is a system with deep oxidation subsidiary reaction and the reaction heat of subsidiary reaction is greater than that of ethylene oxidation to acetic acid. So the increasing of selectivity is helpful to decreasing the reaction heat. Irregular shape catalyst of through holes is beneficial to increasing selectivity and modifying the transition of heat in catalyst bed.