For synthesis of 2,4-dinitroimidazole(2,4-DNI) from the rearrangement of 1,4-dinitroimidazole(1,4-DNI),microwave heating instead of conventional heating can improve yield of the product and shorten the reaction time from 4~50 h to 10 min. The authors investigated the effects of microwave power for heating,reaction time,solvent type and concentration of 1,4-DNI in chlorobenzene on the yield of 2,4-DNI. Based on this investigation the optimal rearrangement conditions would be as follows: microwave power: 375 W, heating time: 10 min,solvent: chlorobenzene,concentration of 1,4-DNI: 10%. Under the conditions listed above,the yield of resulting 2,4-DNI can be up to 95% with a melting point of 265-268 ℃(decomposition).