Research conclusions: The ultimate tensile strength at room temperature of hot-rolled rails is 1 080 MPa, and hardness of tread is up to 300 HB. The H and O contents of finished rails are 0. 5 x 10-4% and 12. 3 x 10-4% respectively. The microstructure of tread and gauge comer is consist of pearlite and a little ferrite. The largest residual tensile stress in rails bottom is 200. 2MPa. The fracture toughness ( K1C) at -20℃is 32. 5 MPa?m1/2. When the stress intensity factor (?K) is 10 MPa?m1/2}and 13. 5 MPa?m1/2，the fatigue crack growth rate(da/dN ) is respectively 9. 55 m/Gc and 31.98 m/Gc. All results show that the 68kg/m hot-rolled rails satisfy requirements of”tentative technical specifications of 68kg/m rails"，and could be laid on heavy haul railway line.