Abstract: A new fatigue test called Reliability Fatigue Test Method is advanced in the paper according to the mathematics theory on the relation of frequency distribution between fatigue strength and fatigue lifetime based on the component basic property of fatigue destroy. By means of this method, the component distribution law of fatigue strength can be easily to analyze the fatigue strength reliability of mechanical component. High effeciency of success and the short testing period are some of advantages of this method and a great number of spring parts fatigue test done by author show the feasibility of the method.