Catalysted by Fe2O3,The synthesis of 1,2-dimethyl-4-tert-butylbenzene was performed with tert-butyl chloride and o-xylene .This new method is friendly to environment,because we didnot use any solvent and the reaction is simply compeleted without any wasts.Then,we studied the essential factors that maybe influence reaction,for example,temperature,time,mole ratio of tert-butylchloride to o-xylene,the amount of catalyst and etc.The results show that at 50 ℃,catalysted by Fe2O3,we can get the target product in 2.5 hours,A catalyst of Fe2O3 ensuring production of 1,2-dimethyl-4-tert-butylbenzene with a 97.77 % yield and selectivity of o-xylene conversion to the target product of 99.48 % was developed。The product of 99.3 % purity（by Gas chromatogram） is confirmed by 1HNMR.