The object of this study is investigation of compatibility on RMC model for fatigue evaluation under real loading condition and the computer programming to apply to the fatigue design, safety control and estimating the remaining service life of the structural members. The procedure of this study is to measure stress cycles from the railway bridge, to simulate the data to the probability density function according to the frequency distribution of stress range and to make the fatigue test by simulated loading model and equivalent one(RMC). Especially in the fatigue test, the number of stress cycles per block was $10^3$ that is reported the most similar to the real loading condition. To make it possible, the micro computer connected with fatigue test machine was used, so it controled the irregular stress range automatically. The result was that the variation of stress ranges; is the faster velocity of traffic loads is the faster on bridge, the fatigue damage is the more increased. And the compatible way to evaluate the fatigue behavior of structural steel member under real loads was the RMC model of the equivalent stress concept.