The fatigue crack behavior of a silicon carbide was tested at an elevated temperature. The fatigue phenomenon is observed in air, but not in a vacuum. The crack growth process consists of three stages. In the first stage the crack shows a rapid growth rate, but decreases in the second stage. In the third stage, the growth rate continues to decrease under low stresses, but increases again, and the material begins to fracture under high stresses. The fatigue lifetime is subjected to the time of the second stage, in which the well-known power-law relationship between the crack growth rate and the stress intensity factor dc/dt=AKn does not hold. Furthermore, the cyclic fatigue lifetime does not depend on the number of cycles but does depend on the loading time.