Abstract: The microstructure morphology of decarburization of GCr15 steel bearing ring was discussed, and the mechanism of full decarburization and local decarburization was analyzed. The results show that the basic reason for the formation of surface decarburization of GCr15 steel bearing ring is the lower furnace carbon potential during spheroidizing annealing. One of the reason of local formation of lamellar pearlite is selective crystallization.