The Enclosed-arc welding simulated at the laboratory level was applied to the rail steel of high carbon Cr-Ti alloy containing 0.1 w/oTi. After welding, the impact toughness and the fatigue properly of the welded zone were investigated in connection with the austenite grain size and microstructure. Also these mechanical properties of the high carbon Cr-Ti alloy rail steel were compared with those of common rail steel. According to the experimental results, the impact toughness and the fatigue property at HAZ, on the whole, increased as the pearlite interlamellar spacing and austenite grain size became finer. And there was little variation in the fatigue property of the welded zone because of the effect of pre-worked notchs at the alloy rail steel. As the cementite spheroidizing phenomena were remarkable at HAZ, both the impact toughness and the fatigue strength increased. Throughout the welded zone of the high carbon Cr-Ti alloy rail steel, austenite grain size showed little variation, and had ASTM No.4.5-5 at a distance of 25㎜ from the bond. The impact and fatigue properties of the high carbon Cr-Ti alloy rail steel were found to be superior to the these of common rail steel.