Abstract: Cracks were found on the inner surface of a GCr15 steel bearing ring after machining. Macroscopic observation, chemical composition analysis, scanning electron microscopy and energy spectrum analysis were used to analyze the cracked rings. The results show that during the production process of the ring, the piercing plugs broke and foreign particles embedded in the matrix, disrupting the continuity of the matrix and ultimately led to cracking on the inner surface of the ring.