The end-cleavage of 25CrMnSi steel CCT samples treated by a high-power CW CO2 laser are investigated for improving the miorostructure of the material, changing the stress distribution of the end-cleavage and enhancing the performances of the fatigue failure resistance of the material. It has been shown that △Kth of the materials is increased, the fatiguelifetime is prolonged by over two times and is reduced after laser treatment. The approximate empiric formula is obtained relating the cycle number N of the fatigue crack spread to the laser treatment parameters by means of statistic analysis of the experimental data.