To evaluate the fatigue behavior of rail steels, fatigue test was performed by CT-type specimen under constant amplitude loading. From the analysis results that presented on the relationships between crack growth rate and stress intensity factor, the effect of the following parameters on the fatigue crack growth behavior were studied ; crack orientation and stress ratio. From this study, it is known that SL-orientation crack is faster than LT- and TL-one in the crack propagation velocity. According to the evaluation of stress ratio effect in rail steels, fatigue crack growth curve is the best fit in a straight line without regard to stress ratio in case of expression by combination of ${Delta}K$ and $K_{max}$. And Crack growth rate proposed by Crooker & Lange is suitable.