The effect of the microstructure of 35KhN2MFA steel on the mechanic properties under static and dynamic loading has been investigated. Different microstructures were obtained as a result of the following heat treatment condition: 1) quenching from 740 - 1100 C; 2) isothermal quenching at 360 C; 3) tempering at 300 - 550 C; 4)thermocycling. The impact - fatigue test was carried on an impact testing machine with impact energy of 1.087 J. Increasing of the quenching temperature leads to increasing of fatigue life from 5700 (Tq=740 C) to 10100 cycles (Tq=1100 C) without changes in strength (σb=1740 MPa) and with some decreasing of ductility and impact toughness. Isothermally quenched and high tempered specimens shown high fatigue life (N=12000 - 13500 cycles), but lower strength (σb=1330 MPa). The specimens after thermocyclic treatment reveal the best combination of mechanical properties under static and dynamic loading.