Abstract: The reason on cracking failure of GCr15SiMn steel bearing terrule had been analyzed by OM,SEM and EPMA etc.The primary reason of terrule cracking is originated from carbide aliquation and reticulation distributing of metallurgical structure because of low forging ratio and high beginning forging and ending forging temperature,which increased brittleness markedly.During quenching process,the cracks are facilitated by such factors as heat stress and phase transition stress,then the cracks are extended by procedure external grinding force,which induced terrule failure.