he 60 rails on Shanghai Metro Line 1 from Jinjiang paradise station to Xinzhuang station have wounds of different degrees at the present time. Outer rails on curve railway have corner fine cracks on the inner flank, and some cracks evaluate down and lead to core wounds. Initially corner fine cracks expand slowly on the early stage, with the times of fatigue loads increasing crack depth expanding speed rate dh/dN breaks.The times of fatigue loads at turn over point is defined as the initial life of corner fine cracks.