Four grouped rectangle specimens with thirty four samples, plus eighteen samples for fatigue limits, are tested for constructing the fatigue reliability curves of China grade B cast steel wheel. It reveals that fatigue cracks commonly initiated from the surface weakest phases and grew with typical fatigue striations and sub-cracks perpendicular to the growth direction. Cyclic plastic seems to be strengthened as cyclic stressing level increasing. Fatigue reliability curves are constructed on a consideration of addressing the real super long life. They are evaluated by a concurrent probability extrapolation method. And the measured curves verified that appropriate description has been reached on the test data.