Abstract: This paper deal with catalyzing action of rare earth elements(RE) on carburzing process.The results showed that the carburzing process of steel is accelerated obviously under the action of cativity and catlysis of RE,the permeating rate is increased by a factor of 20%-30% compared with conventional carburzation.It is proved that Re permeated in surface of the steel.In the treatise the mechanism of catalytic effect RE in catburzing process is also discussed.