Up to now，there is no reasonable explanation for some special effects in microwave heating on chemical reaction，consequently，the non-thermal effect is an uncertain problem pending solution.At the same time，there are no rigorous and effective methods to guide the design of microwave-assisted chemical reactor.It is necessary to develop numerical methods to simulate the interaction between microwave and chemical reaction.In this paper，the empirical formula of effective permittivity proposed by Huang et al was used to calculate effective permittivity in acetone iodation at any temperature and time of the reaction，and the kinetic equation，Maxwell’s equation，and heat transport equation were solved for the distribution of electromagnetic field and temperature in the reaction process.At last，the calculated results were compared with the measured results to verify this calculation.This method offers high potential application to the explanation of some specific phenomena in the microwave heating for chemical reactions and guides the design of microwave-assisted chemical reactor.