Abstract: The effect of quenching temperature and tempering temperature on the microstructure and mechanical properties of steel bars used in prestressed concrete is studied. The results show that when the tempering temperature is certain, tensile strength increases first and then decreases as the quenching temperature increases, and the suitable quenching temperature is 900℃; when the quenching temperature is certain, the tensile strength decreases gradually with the increasing of the tempering temperature; the elongation at break of the steel bar tempered at 370~460℃ can satisfy the above 5% requirement, and combined with standard requirement that the tensile strength should be above 1 420 MPa, the suitable tempering temperature of steel bar for prestressed concrete is 400℃.